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THE TECH FAQ
Newsgroups: rec.arts.movies.tech,rec.answers,news.answers
Subject: rec.arts.movies.tech FAQ [1/4]
Followup-To: poster
From: snorwood@nyx.nyx.net (Scott Norwood)
Organization: Nyx Net, the spirit of the Night (www.nyx.net)
Message-ID: <943097955.129955@iris.nyx.net>
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Date: Sat, 20 Nov 1999 11:54:09 GMT
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Last-Modified: 2/98
Version: 2.00
_________________________________________________________________
rec.arts.movies.tech
Frequently Asked Questions (FAQ)
(with answers)
Version 2.00
(supersedes all previous versions)
February 14, 1998
Compiled, Edited, Maintained by
Scott E. Norwood
snorwood@nyx.net
_________________________________________________________________
Copyright İFebruary 14, 1998, by Scott E. Norwood
This document may be freely distributed by electronic, paper, and
other means, provided that it is distributed in its complete,
unmodified form for non-commercial and/or educational purposes.
Commercial use of the material contained herein is not permitted,
unless prior written permission is obtained from the copyright holder.
Others who have contributed to this document retain the rights to
their own contributions (which are noted).
DISCLAIMER:
The compiler of this document has attempted to make every reasonable
effort to ensure that any information contained herein is accurate and
complete. However, the compiler is unable to assume responsibility,
legal or otherwise, for any inaccuracies, errors, or omissions
relating to the information contained below. All of the information
contained in this document is believed by its compiler to be held in
the public domain. The compiler is not affiliated with any of the
companies whose products are mentioned here, nor does he necessarily
endorse these products. All statements about such products are for
informational use only. U.S. trademarks are indicated by (tm) where
applicable, and are used here without the permission of their owners.
_________________________________________________________________
Contents
* Contents
* 1 Introduction
+ 1.1 Purpose of rec.arts.movies.tech
+ 1.2 Purpose of this FAQ list
+ 1.3 Standards of ``netiquette'' for news posting
+ 1.4 Credits
+ 1.5 Where is the latest version of this FAQ available?
+ 1.6 What is the best way to print this FAQ?
+ 1.7 What changes have been made to this FAQ since previous
versions?
o 1.7.1 Version 0.01 (6/7/96)
o 1.7.2 Version 0.02 (6/17/96)
o 1.7.3 Version 0.03 (11/17/96)
o 1.7.4 Version 1.00 (11/15/97)
o 1.7.5 Version 2.00 (2/15/98)
* 2 Motion Picture Formats (original cinematography)
+ 2.1 Which film gauges are currently in common usage for
original cinematography?
o 2.1.1 35mm - Standard Theatrical Gauge
o 2.1.2 16mm - Home Movies/Television/Low-Budget
Theatrical
o 2.1.3 8mm - Cheaper Home Movies
o 2.1.4 Super 8mm - Better Home Movies
o 2.1.5 65mm - Better Theatrical Features
+ 2.2 Which formats are common for 8mm cinematography?
+ 2.3 Regular 8mm/Super 8mm (standard 8mm/super 8mm frame)
+ 2.4 Which formats are common for 16mm cinematography?
o 2.4.1 16mm (standard 16mm frame)
o 2.4.2 Super 16mm (HDTV/35mm blowup frame)
+ 2.5 Which formats are common for 35mm cinematography?
o 2.5.1 35mm (old silent frame)
o 2.5.2 35mm (standard Academy frame)
o 2.5.3 35mm Anamorphic (standard `wide screen' theatrical
frame)
o 2.5.4 35mm VistaVision (visual effects frame)
o 2.5.5 Super 35mm (production format for release prints
of various formats)
+ 2.6 Which formats are common for 65mm cinematography?
o 2.6.1 65mm (standard 65mm theatrical frame)
o 65mm (IMAX (tm) /OMNIMAX (tm) )
o 65mm (SHOWSCAN (tm) )
* 3 Motion Picture Formats (release prints intended for projection)
+ 3.1 Which film gauges are currently in common usage for
release prints intended for projection?
+ 3.2 Why is wide-gauge film manufactured in the 65mm width for
motion- picture cameras, and in 70mm for release prints?
+ 3.3 Which formats and aspect ratios are common for 8mm
release prints?
o 3.3.1 Regular 8mm/Super 8mm
o 3.3.2 Regular 8mm/Super 8mm Anamorphic
+ 3.4 Which formats and aspect ratios are common for 16mm
release prints?
o 3.4.1 Regular 16mm
o 3.4.2 16mm Anamorphic
o 3.4.3 Super 16mm
+ 3.5 Which formats and aspect ratios are common for 35mm
release prints?
o 3.5.1 35mm Silent Frame
o 3.5.2 35mm Academy Frame
o 3.5.3 35mm `Flat' Wide Screen Formats
o 3.5.4 35mm Anamorphic Frame
o 3.5.5 Projecting Multiple Formats
+ 3.6 Which formats and aspect ratios are common for 70mm
release prints?
o 3.6.1 70mm Standard Frame
o 70mm IMAX (tm) /OMNIMAX (tm) 15-Perf Frame
* 4 Motion Picture Sound Formats (release prints intended for
projection)
+ 4.1 What analog sound formats are common for 8mm release
prints?
o 4.1.1 Regular 8mm Magnetic (monophonic)
o 4.1.2 Regular 8mm Magnetic (monophonic or stereo)
o 4.1.3 Regular 8mm Optical (monophonic)
+ 4.2 What analog sound formats are common for 16mm release
prints?
o 4.2.1 16mm Optical (monophonic)
o 4.2.2 16mm Magnetic (monophonic)
+ 4.3 What analog sound formats are common for 35mm release
prints?
o 35mm Optical (monophonic, stereo, or Dolby Stereo (tm) )
o 4.3.2 35mm Magnetic (four-track stereo)
+ 4.4 What analog sound formats are common for 70mm release
prints?
o 4.4.1 70mm Magnetic (six-track stereo)
+ 4.5 What are the three commonly used digital sound formats
for 35mm release prints, and how do they work?
o 4.5.1 General Information
o Digital Theater Systems (DTS) (tm)
o Sony Dynamic Digital Stereo (SDDS) (tm)
o Dolby (tm) Spectral Recording Digital (SR-D) (tm)
+ 4.6 What methods have been used for digital sound in formats
other than 35mm?
* 5 Motion Picture Presentation (theatrical projection)
+ 5.1 What type of projection and sound equipment is commonly
used for commercial theatrical presentation?
o 5.1.1 Projector/Lamphouse
o 5.1.2 Sound System
+ 5.2 What are some specific examples of a common projection
setup?
+ 5.3 What are the differences between xenon, and carbon-arc
lamphouses?
+ 5.4 How are `seamless' manual reel changeovers accomplished?
o 5.4.1 Shipping Configurations for 35mm Prints
o 5.4.2 Changeover Procedures
+ 5.5 How does a platter system work?
o 5.5.1 Platter Configurations
o 5.5.2 Platter Operation
+ 5.6 How are multiple projectors interlocked to run the same
piece of film in multiple auditoria?
+ 5.7 What are the industry standards for image brightness and
screen reflectivity?
+ 5.8 What are the industry standards for sound levels in a
mono setup?
+ What are the industry standards for sound levels in a Dolby
Stereo (tm) setup?
+ 5.10 How does a dual-format (35/70) projector work, and how
is the changeover made between formats?
+ 5.11 What are the differences between nitrate-, acetate-, and
polyester-based print stocks?
o 5.11.1 Nitrate Base/Triacetate (Safety) Base
o 5.11.2 Polyester Base
+ 5.12 What is the best way to avoid the static and shedding
problems common in polyester prints?
+ 5.13 What precautions are necessary when projecting nitrate
prints?
+ 5.14 What are the proper procedures for print inspection
prior to showing a film?
+ 5.15 What other problems are common in film projection, and
how does one fix them?
* 6 Film Laboratories
+ 6.1 What are the differences between reversal and negative
film, and which is the most common?
o 6.1.1 Differences Between Reversal and Negative Films
o 6.1.2 Uses for Reversal and Negative Films
+ 6.2 What is a `one light work print'? A `timed work print'?
+ 6.3 What does a negative cutter do?
o 6.3.1 General Information on Negative Conforming
o 6.3.2 A & B (& C) Roll Conforming and Printing
+ 6.4 What is timing/color timing, and how does it affect the
look of filmed images?
+ 6.5 What is an `answer print'?
+ 6.6 What is an `interpositive'? An `internegative'?
+ 6.7 What is a `check print'?
+ 6.8 What is a `release print'?
+ 6.9 What is the difference between release prints made for
projection with tungsten lamps and release prints made for
projection with xenon lamps?
+ 6.10 What is a `low-contrast print'?
+ 6.11 What is `green film'? Why isn't it green?
+ 6.12 What are currently the standard reel/can sizes for the
various film formats?
+ 6.13 How can I process reversal films at home?
* 7 Film for Videotape and Television (and vice-versa)
+ 7.1 How is the frame-rate difference worked out when film is
displayed on television?
o 7.1.1 European Television Standard
o 7.1.2 U.S./Canada/Japan Television Standard
+ 7.2 What are the various methods used to display film on
television or videotape? Which are the most common?
o 7.2.1 Film Chains
o 7.2.2 Flying Spot Scanners
+ 7.3 How are film negatives cut to match an edit done on
videotape?
+ 7.4 How is the sound re-synced to the film to match an edit
and mix done on videotape?
+ 7.5 What formats of videotape are most commonly used for film
post- production?
o 7.5.1 Television Films
o 7.5.2 Theatrical Films
+ 7.6 What formats of videotape are most commonly used for
television broadcast of filmed material?
+ 7.7 How are 70mm films displayed on television or videotape?
+ 7.8 How is material originated on videotape transferred to
film for theatrical projection? How is the sound synced?
* 8 Opinions
+ 8.1 What is the most workable method of projecting super-16mm
workprint with separate fullcoat magnetic soundtrack?
o 8.1.1 Double-Band Interlock Projector
o 8.1.2 Standard Projector Interlocked With Dubber
+ 8.2 What is the likely future for 2.5-perf 35mm release
prints?
+ 8.3 Which films are good examples of wide screen composition?
+ 8.4 Which films are good examples of multi-channel sound
mixes?
+ 8.5 What are some recommendations for long-term film storage?
* 9 Obsolete Film Formats
+ What was `Cinerama' (tm) ? How did it work? Why did it become
obsolete?
+ 9.2 What was `Techniscope'? How did it work? Why did it
become obsolete?
+ What was `Ultra Panavision 70 (tm) ' a.k.a. `MGM Camera 65
(tm) '? How did it work? Why did it become obsolete?
+ What was `CinemaScope (tm) 55'? How did it work? Why did it
fail?
* 10 Miscellaneous
+ What is THX (tm) certification, and what standards are
necessary for a theater which wishes to obtain it?
+ 10.2 What equipment is necessary for a `home cinema' for 16mm
and where can it be begged for/purchased?
+ 10.3 What equipment is necessary for a `home cinema' for 35mm
and where can it be begged for/purchased?
+ 10.4 Where can one purchase or rent release prints in
8/16/35/70mm?
+ 10.5 What are the various processes used for color in motion
pictures?
+ 10.6 What are the various frame rates which have been used
for motion pictures?
+ 10.7 What are the three different types of perforations used
for 35mm release prints?
+ 10.8 What is a `reverse scanning solar cell' and how does it
improve sound reproduction?
+ 10.9 Who is R. Michael Hayes, and why are they saying those
things about him?
+ 10.10 Why are `trailers' called `trailers' when they are
spliced after the `leader' of a movie?
+ 10.11 What books are useful for one interested in film
formats and presentation?
+ 10.12 What magazines and other publications are useful for
one interested in film formats and presentation?
+ 10.13 What online resources exist for one interested in film
formats and presentation?
* 11 Reference Information
+ 11.1 What are the footage/time conversions for the various
film formats?
+ 11.2 What are the lens focal length/image size conversions
for the various film formats?
o 11.2.1 16mm Chart
+ 11.3 What are the standard locations for reel-change cue
marks on U.S. release prints in the various film formats?
1 Introduction
1.1 Purpose of rec.arts.movies.tech
This is one of many USENET newsgroups in the rec.arts.movies.*
hierarchy; its purpose is to facilitate the discussion of the many
technical details associated with motion pictures. Topics often
include questions about projection issues in theaters, film and sound
formats and aspect ratios, equipment used in film production and
presentation, and, occasionally, visual effects used in motion
pictures. This group is intended for text messages only. Binaries
should be uuencoded and posted to the appropriate groups within the
alt.binaries hierarchy, or, preferably, made available through the
World Wide Web or anonymous FTP. As is the case with most USENET
groups, messages posted in HTML or any other non-plaintext format are
strongly discouraged.
1.2 Purpose of this FAQ list
As is the nature with USENET groups, similar questions and topics are
often raised. Thus, in order to save network bandwidth
(information-carrying capacity), the time of those who read the
groups, and to promote more interesting discussions, a list of
frequently asked questions (FAQs) and their answers is often
assembled, and posted regularly to the newsgroup. It should be
mentioned that the purpose of the FAQ is not to inhibit or restrict
newsgroup discussions, but rather to encourage more enlightening
discussions by freeing the group's readers from the burden of
regularly answering the same or similar questions.
1.3 Standards of ``netiquette'' for news posting
New readers of USENET news would do well to spend a few minutes
reading the information posted in the group news.announce.newusers, as
well as reading the posts made by other readers of
rec.arts.movies.tech prior to posting their own messages to it.
Additionally, it would likely benefit everyone who reads the group if
the few points below were kept in mind when posting:
1.
Make subject lines descriptive! While rec.arts.movies.tech is
not overflowing with posts, it still saves time for its readers
to ensure that subject lines are reflective of the content of
the post. Don't use ``70mm'' as a subject head. Instead, use
something like ``Correct Aspect Ratio for 70mm?''. Don't use
``projector,'' but rather use ``FS: Bell and Howell sound
super-8 Projector.''
2.
Don't post excessively long messages (see warning about posting
of binaries above in 1.1).
3.
When quoting from someone else's message in a followup post, be
sure to check that the person whom you're quoting actually
wrote the material you quote. Also, try to edit quoted material
for length (but never content)-don't quote 700 lines of
previous posts and then type ``I agree'' at the bottom. This
type of post serves the interests of no one.
4.
Don't post blatantly commercial material, particularly if the
material does not fall under the charter of
rec.arts.movies.tech. ``Garage Sale''-type posts are considered
to be acceptable, as long as they are non-commercial in nature,
and are not posted regularly.
5.
Don't type in all caps (LIKE THIS). Nearly all terminals in use
today (as well as personal computers) will support lower-case
letters, which are easier to read for most people.
1.4 Credits
[perpetually under construction]
Thanks to the following individuals for reviewing the first edition of
this FAQ, and correcting my numerous errors and omissions: Andrew
Shepherd cinema@falcon.cc.ukans.edu, David Richards
daverich@netcom.com, Martin Gignac martyg@sympatico.ca, David Pomes
mrspoque@aol.com, Scott Marshall WideGauge@aol.com, Gordon McLeod
gmcleod@idirect.com, Stephen Bradley spbradley@earthlink.net, and
Clive Tobin tobin@nwus.com. I am duly humbled. Special thanks to Ed
Inman edinman@teclink.net for his great information on home processing
of reversal films (included in the 'Film Laboratories' section). Ralph
Daniel 104574.2404@compuserve.com provided the Cinerama Features List
(included in the 'Cinerama' section), which was appended to by Vince
Young veyoung@aol.com. Jim Harwood jharw91601@aol.com and Frank Wylie
fwylie@infinet.com provided the valuable recommendations on film
storage, located in the `Opinions' section.
1.5 Where is the latest version of this FAQ available?
The current version will always be available for viewing on the World
Wide Web at:
http://www.nyx.net/~snorwood/faq.html
The current version of the FAQ is also posted monthly to
rec.arts.movies. tech, rec.answers, and news.answers. It is available
via anonymous FTP from the various FAQ archive sites, most notably
rtfm.mit.edu and is located in the
/pub/usenet-by-group/rec.arts.movies.tech directory.
I will also send this document by email to anyone who requests it.
Just send your request to the following Internet address:
snorwood@nyx.net. I will send it out as soon as possible.
Comments, corrections, additions, and suggestions are always
encouraged. Please either post them to rec.arts.movies.tech, or,
preferably, email them directly to me, and I will incorporate them
into future versions of this FAQ.
1.6 What is the best way to print this FAQ?
Beginning with version 2.00, this file is available in several
formats: a plaintext version (which is posted to r.a.m.t), an HTML
version (designed for viewing on the World Wide Web), a raw PostScript
version, and a DVI file.
The plaintext version is formatted for 80 columns, and can be printed
on a standard 80-column dot-matrix or laser printer (it looks best at
six lines per inch vertical spacing). This file may be loaded into
almost any word processor or text editor, and printed from within that
environment, or may be sent directly to the printer device. If a
choice of typefaces is offered, be sure to select one of the
`monospace' variety (Courier, Prestige, Monaco, etc.) to ensure that
the ASCII diagrams below are properly reproduced; also, be sure to set
the margins to allow for at least 80 characters of text per line.
For those who have access to the World Wide Web, the HTML version of
this document can be printed from within a standard web browser (Lynx,
Mosaic, Netscape, etc.). The content is identical to the plaintext
version, although the HTML version looks slightly better.
The PostScript file provides the best-looking output, and can be
viewed online using software such as ghostscript or ghostview, or it
may be printed using a PostScript-capable printer.
The DVI file can be printed on DVI (Device Independent) printers, or
may be converted into other formats.
1.7 What changes have been made to this FAQ since previous versions?
1.7.1 Version 0.01 (6/7/96)
1.
(no previous version)
1.7.2 Version 0.02 (6/17/96)
1.
Record of modifications (this list) begun.
2.
FAQ broken up into four sections (from the original two) in
order to accommodate future additions and modifications;
hopefully, four sections will be enough to accommodate all
foreseeable changes and additions, as more than four sections
can be confusing to new readers (who most need to read the
FAQ).
3.
Third hierarchy of section numbering added to many sections of
information.
4.
Disclaimer modified slightly, and reformatted to take up fewer
lines.
5.
Trademark indications added to trademarked format/process names
(I know they look silly, but I need to protect myself!).
6.
Names added to `Credits' section.
7.
Numerous corrections/additions/rearrangements/wording changes
made to entire FAQ.
8.
ASCII diagrams of film frames `flipped' to conform to standard
film-frame diagram format (i.e. to show what it would look like
to project a `complete' film frame onto a large screen).
9.
Information on home processing of reversal film added.
10.
Various categories relating to obsolete processes have been
deleted, as they all can be included in the section devoted to
obsolete formats.
11.
`Opinions' section substantially reduced, due to liability
concerns.
1.7.3 Version 0.03 (11/17/96)
1.
Numerous corrections/additions/rearrangements to entire
document, in preparation for v.1.00.
1.7.4 Version 1.00 (11/15/97)
1.
General overhaul of all sections; long-overdue extensive
corrections and updates.
2.
Expansion of several sections (most notably those regarding
Cinerama and other widescreen processes).
1.7.5 Version 2.00 (2/15/98)
1.
Entire file reformatted in LaTeX, to automate production of
multiple formats (ASCII, HTML, PostScript, etc.). Although this
document was originally posted to r.a.m.t in four parts (for
compatability with older news software), it will now be posted
as a single large file.
2.
Many sections re-worded for clarity and style.
3.
Several factual corrections made.
_________________________________________________________________
2 Motion Picture Formats (original cinematography)
2.1 Which film gauges are currently in common usage for original
cinematography?
2.1.1 35mm - Standard Theatrical Gauge
The standard gauge for theatrical motion pictures has always been
35mm. This rather arbitrary width supposedly originated with an
agreement made between Thomas Edison's associate, William K. L.
Dickson, and George Eastman in the early days of motion pictures,
because the original Kodak (tm) box camera used film which was 70mm
wide, and a 35mm motion-picture stock could inexpensively be derived
from this stock by slitting it lengthwise and perforating the edges.
This gauge remains the most widely used for theatrical features, and
is also commonly used for television work.
2.1.2 16mm - Home Movies/Television/Low-Budget Theatrical
In 1923, 16mm was introduced by Kodak (tm) for home-movie use (just
after 9.5mm, now a nearly dead amateur format, was introduced in
Europe). Supposedly this width was chosen instead of 17.5mm (half of
the commercial standard) for safety reasons-at the time 35mm stock was
manufactured on a nitrate base, making it extremely flammable. This,
of course, would be too dangerous for home use, and so 16mm was
manufactured on a so-called `safety film' acetate base, which was not
flammable. This non-even division of 35mm discouraged the cutting of
16mm film from dangerous nitrate stock. Since its early days, 16mm has
become the `jack-of-all-trades' of film formats, finding use for
everything from home movies through medium-budget features. Most
current use is for television work and low-budget features. The
Super-16 format, described below, originated in the 1970's, as an
inexpensive means for providing additional negative area within the
16mm format.
2.1.3 8mm - Cheaper Home Movies
In 1932, 8mm film was introduced in order to bring home movies to the
masses. This `regular 8mm' is standard 16mm film which has twice as
many perforations as 16mm. It is run through an 8mm camera normally,
exposing one half of its width. The take-up spool then is flipped and
the film is reloaded, so as to run through the camera opposite to its
original direction, exposing the other half of its width. After the
film is developed at the laboratory, it is slit down the middle and
the pieces are spliced together, resulting in an 8mm film. Regular 8mm
is not commonly used now, given the superiority of Super 8mm, and the
film is difficult to find now (although it is still available). Unlike
the other major formats mentioned here, cameras for regular 8mm are no
longer manufactured.
2.1.4 Super 8mm - Better Home Movies
In 1965, it was found that the perforations on 8mm film could be made
smaller in order to allow for a larger image area, and thus a sharper
picture. This resulted in `super-8mm' film, which is sold pre-loaded
into plastic cartridges (as opposed to the metal spools of regular
8mm), which snap into the camera. Unlike other gauges, the `pressure
plate' (the piece which provides pressure on the back of the film in
the gate area, in order to ensure that the film lies flat when it is
exposed) is plastic and is built into the cartridge. In other gauges,
it is a (usually) removable (for cleaning) metal plate which is part
of the camera. Super 8mm is now used mostly by students, those
shooting no-budget films, portions of feature films which demand a
super 8mm 'look,' music videos, and some direct-to-TV/video work. A
variant of the Super 8mm format, ``Single 8,'' was sold by Fuji and
possibly other manufacturers, which used the same film stock, packaged
in somewhat different-shaped camera cartridges; cameras were made
specifically for this format. Once processed, film can be projected on
any Super 8mm projector. Current availability of Single 8 cameras and
film stock is unknown.
2.1.5 65mm - Better Theatrical Features
Despite a brief experimental period in the 1920's and 1930's, `wide
screen' motion pictures did become popular among film producers until
the 1950's and 1960's, when television began to pose a threat to their
business. At that time, wide film stocks existed in a number of
widths, but eventually 65mm became the standard film stock for
large-format cinematography. This offered a picture of substantially
higher resolution, steadiness, and apparent color saturation than
standard 35mm film. This format is now used for some theatrical
features, as well as 'special-venue' and 'ride' films (see below).
2.2 Which formats are common for 8mm cinematography?
-
regular 8mm camera frame: .192" x .145"
-
super 8mm camera frame: .224" x .163"
2.3 Regular 8mm/Super 8mm (standard 8mm/super 8mm frame)
As mentioned above, there are two `varieties' of 8mm film, both of
which are still in use. Both of these varieties are commonly shot
`flat' (i.e. without any `anamorphic' horizontal compression), using
standard lenses.
Several frame rates are used in these formats: films shot for silent
projection (no sound-on-film) are usually photographed at 16 frames
per second (fps), 18 fps, or 24 fps. Films shot for sound-on-film
projection run at 18 fps, or, more commonly, 24 fps. Different cameras
provide different combinations of shooting rates.
Regular 8mm commonly comes in 25' and 50' spools, as well as 100'
spools (although the Bolex regular 8mm is the only camera which takes
the 100' spools). Super 8mm comes in 50' and, less commonly, 200'
cartridges. Most cameras are only capable of accepting the 50'
cartridge, though. Eastman Kodak (tm) once produced super 8mm `sound'
cartridges, which contained film with pre-applied magnetic stripes
along the edges, designed to be recorded in camera. Production of new
pre-striped super 8mm film was discontinued in the fall of 1997, due
to lack of demand.
regular 8mm film frame: super 8mm film frame:
(note big perforations) (note small perforation)
| | | |
| -------------- O | | ---------------- |
| | Small | | | | Larger | |
| | Image | | | | Image |o| <--- Smaller
| | Area | | | | Area | | Perforation
| -------------- O | | ---------------- |
| | | |
|<------ 8mm ----->| |<------ 8mm ----->|
2.4 Which formats are common for 16mm cinematography?
2.4.1 16mm (standard 16mm frame)
-
standard 16mm camera frame: .404" x .295"
Like 8mm and super 8mm, 16mm films are almost always shot `flat,' as
few anamorphic camera lenses are currently available, although they
were somewhat more common in the 1960's for sophisticated amateurs.
The 16mm film stock itself has not changed since the format's
introduction, and it is almost always double-perforated (i.e. it has
sprocket holes on both sides), though few cameras actually require
this (the Maurer and the Mitchell 16mm models do, however).
Double-perf camera stock is becoming rarer, however, with the increase
in Super 16mm production; it is now special-order from Eastman Kodak
(tm) and other manufacturers.
The film itself comes either wound tightly around a plastic `core,'
for loading into a camera magazine (either in a darkroom, or a
portable `changing bag'), or, for 100' and 200' lengths, mounted on
small metal spools (like those for regular 8mm), which can be loaded
into the camera in moderately bright daylight. Professionals usually
use 400' and (rarely) 1200' lengths of the film. (The Panavision 16 is
the only currently-available camera which will take the 1200' rolls;
old newsreel cameras, such as the Auricon (which is still available on
the used market), also can take this large size).
Films shot in 16mm almost always run at 24 frames per second (fps),
with the exception of many silent home movies which are sometimes shot
at 16 fps. European television films are photographed at 25 fps to
match the frame rate of the PAL television standard. Occasionally,
U.S. television films are shot at 29.97 fps or 23.976 fps to match or
nearly match the TV standard, respectively.
As with super 8mm, magnetic-striped 16mm raw stock was once available
for use in cameras with built-in recording heads, although pre-striped
stock is no longer available. It was primarily used for TV newsfilm
applications, until 3/4" videotape replaced 16mm for newsgathering in
the late 1970's/early 1980's.
2.4.2 Super 16mm (HDTV/35mm blowup frame)
-
super 16mm camera frame: .488" x .295"
In the 1970's, super 16mm was developed as a filming format primarily
for productions which were to originate on 16mm (supported heavily by
Aaton (tm) , the French camera manufacturer), but be ``blown up'' to
35mm for theatrical release (as few commercial theaters have 16mm
projectors). The image was made wider, extending into the far edge of
the film, formerly occupied by an extra set of perforations on camera
film or a soundtrack on release prints (unlike regular 16mm, camera
film for super 16mm shooting must be `single-perf'-i.e. it has
sprocket holes on only one edge, with the other edge left for the
image). This provides a higher-resolution image when the film is blown
up to 35mm, because there is a larger image area, and because there is
less cropping of the image to fit the usual American 35mm aspect ratio
of 1.85:1, or the European ratio of 1.66:1. The disadvantage, though,
is that it is not a projection format, as a single piece of 16mm film
cannot accommodate both the larger image and a soundtrack.
Some producers are shooting TV shows on super 16mm, with the intent of
re-transferring the negatives to videotape when and if high definition
television (HDTV) comes into widespread use. The wider aspect ratio is
very close to the proposed U.S. HDTV standard of 1.77:1 (16/9), and so
super 16mm films could be shown with little cropping, whereas a 1.37:1
picture would either have the top and bottom edges cropped, or the
sides masked inward to fit on an HDTV screen (yielding a very small
picture). Presumably, then, super 16mm is a way for producers worried
about upcoming technological changes in television to `future proof' a
television show, so that it can be presented in any form, with the
highest quality images allowed by the format chosen for future TV
receivers.
16mm film frame: super 16mm film frame:
| | | |
| O--------------O | |-----------------O|
| | Image | | Image area -->| Image ||
| | Area | | extends to | Area ||
| O--------------O | edge of |-----------------O|
| | film. | |
|<----- 16mm ----->| |<----- 16mm ----->|
2.5 Which formats are common for 35mm cinematography?
-
35mm silent camera frame: .980" x .735"
-
35mm Academy camera frame: .864" x .630"
-
35mm ``Super 35'' camera frame: .980" x .735"
-
35mm VistaVision camera frame: 1.485" x .991"
-
35mm Anamorphic camera frame: .864" x .732"
2.5.1 35mm (old silent frame)
Early films were all shot with this camera apeture prior to the advent
of sound-on-film. When sound was first introduced, a variety of odd
aspect ratios (including an almost 1:17 square picture) were
considered, as the image area had to be narrowed in order to leave
space for the soundtrack. Silent 35mm films were shot at roughly 16
frames per second (fps), using hand-cranked cameras and projectors. In
practice, speed varied substantially even throughout a single roll,
and among different titles.. For this reason, running times are almost
never listed for silent films; instead, length is listed as number of
reels or number of feet. The advent of sound standardized filming
speed at 24 fps. When silent films are shown today at 24fps, they
often appear `sped up' and tend to look unnatural.
2.5.2 35mm (standard Academy frame)
In order to maintain a similar projected aspect ratio for both sound
and silent films, the Academy frame was introduced, and has since
become standard. It used the greatest possible width (allowing for
soundtrack space on prints), and reduced the height somewhat in order
to make the projected image retain a 1.37:1 projected aspect ratio.
Earlier silent prints were designed to be projected in a 1.33:1 ratio.
During the `wide screen' craze of the late 1950's and early 1960's,
anamorphic cinematography (a.k.a. `CinemaScope (tm) ,' and, later,
`Panavision (tm) ') became commonplace. In order to advertise their
films as being `wide screen' movies, many producers who had a large
collection of yet-to-be-released 1.37:1 films just cropped off the top
and bottom edges of the frame (including titles and other important
elements), leaving a 1.66:1 or 1.85:1 ratio movie. Later, continuing
through the present, non-anamorphic (`flat') films were composed to
fit on a 1.85:1 screen. These films, however, are still photographed
with an Academy camera frame, although the camera's viewfinder usually
does not show the top and bottom edges. Occasionally, a 'hard matte'
is used in the camera or printer, masking off the top and bottom edges
of the frame. When films are shot `soft matte,' projection errors can
cause undesired elements (such as boom microphones) to show up in the
frame; sometimes, extra area above and below the intended framelines
is visible in TV broadcasts of thse films, as well.
Nearly all 35mm film is shipped wound around plastic cores, and it
comes in 200', 400', and 1000' lengths. Small 100' metal spools are
also available, for use in small windup cameras like the Bell and
Howell (tm) Eyemo.
Most 35mm sound films are shot at 24 fps, as the faster frame rate
both improves the sound quality (with respect to the synchronization
with the image-lower frame rates look strange with lip-sync sound). As
with 16mm, though, some European television films are shot at 25 fps,
to match the TV frame rate, and some US television films are shot at
29.97 or 23.976 fps, to match or nearly match the U.S. TV frame rate,
respectively.
It should be noted that sound is never recorded directly on the 35mm
film while shooting-filming is done in `double system' fashion,
usually using a crystal-controlled camera motor which runs at an exact
speed, along with a crystal-controlled 1/4" tape machine (usually a
Nagra 4.2) or DAT machine.
2.5.3 35mm Anamorphic (standard `wide screen' theatrical frame)
As mentioned above, during the late 1950's and early 1960's, in order
to compete with television, the motion picture industry developed a
number of systems to achieve a wider aspect ratio than previously
used; the idea was to provide a `larger than life' movie experience,
combining huge, curved screens, with improved sound quality. Besides
simply cropping off the top and bottom of the frame, the most
successful such system was `anamorphic cinematography,' initially
introduced as `CinemaScope (tm) ' with The Robe, in 1953. This process
involves photographing a film with a lens which has an anamorphic
element in it. This element `squeezes' the image horizontally by a
factor of 2x. The `squeezed' image fills a large space on the
negative, but, when `unsqueezed' upon projection, yields an image with
a wide aspect ratio. This ratio actually varies slightly depending
upon the exact projector mask which is used, as well as the sound
format.
The disadvantage to shooting in anamorphic is usually that the lenses
used introduce weird types of distortion and lack the depth of field
(front to rear sharpness) of standard `spherical' lenses. For example,
a night scene in a film might contain out-of-focus points of light in
the background; if they were filmed with spherical lenses, the lights
would appear to be circular, but would appear to be vertical ellipses
if they were filmed with anamorphic lenses.
Anamorphic cinematography is still in common usage for major
theatrical films, and is often indicated by the phrase `filmed in
Panavision (tm) ' (if the lenses/cameras were made by Panavision (tm)
), which has displaced `CinemaScope (tm) ' as the usual term for this
process, although many people still refer to anamorphic films as
`scope' films. It is worth noting, though, that companies other than
Panavision (tm) manufacture, rent, and sell anamorphic camera lenses.
Also, the phrase `filmed with Panavision (tm) cameras and lenses'
indicates that Panavision (tm) gear was used, but the film is not in
anamorphic (they rent spherical [non-anamorphic] lenses, too).
2.5.4 35mm VistaVision (visual effects frame)
During the `wide screen' heyday, Paramount developed the `VistaVision'
format (``Motion Picture High Fidelity''), which involved running the
film through the camera sideways, exposing an image eight perforations
wide (the same format as used by 35mm still cameras). This negative
was then optically printed onto a standard release print, of various
aspect ratios, or projected horizontally, with a soundtrack printed on
one edge of the film. This format is now rarely used for feature film
cinematography, although it is often used for background plates and
other visual effects scenes which benefit from the extra negative area
and resulting high resolution of that format, as the negative contains
an area which is four times that of a standard 1.85:1 projected frame.
The actual prints made from this format (at the time when it was
common for features) were intended to be projected in a variety of
aspect ratios. Common ones include: 1.66:1, 1.85:1, and 2:1. Other
aspect ratios were used for projection as well, but never gained wide
acceptance.
2.5.5 Super 35mm (production format for release prints of various formats)
A recent development has been `super 35mm,' which, like super 16mm,
extends the photographed image out into the soundtrack area (it uses
the same frame area as old silent movies), and must be optically
printed onto print stock in order to make projection prints. The
possible advantage to this is that it allows a cinematographer to use
`spherical' (standard) lenses to shoot a film which may eventually be
printed in anamorphic. Spherical lenses are less expensive to rent
than anamorphics, and do not have the characteristic optical
distortion which is common to anamorphic lenses. The disadvantage is
that the images are often grainier than those originally shot with
anamorphic lenses, and the optical printing stage is expensive and
adds its own type of distortion.
Super 35mm is also used by some directors and cinematographers because
they feel that it allows for a less problematic full-screen television
version of the film. Because super 35mm negatives carry more picture
than will eventually be projected, a nicer-looking TV version of the
film can be created. This works by manipulating the area of the film
which is displayed on the television screen, using the extra picture
at the top and bottom of the frame to `fill in' areas which would
ordinarily lack a portion of the image, when the TV frame must center
on a specific area at the edge of the theatrical frame.
Super 35mm prints can be 'extracted' from various portions of the
negative. A `top-extraction' or `common headroom' extraction is made
such that the very top frameline of the super 35mm negative
corresponds to the very top frameline of the print. A `symmetrical' or
`center- extraction' print is made such that equal top and bottom
areas are cropped off of the super 35mm negative. The viewfinder
markings are adjusted to match the chosen format.
Interestingly, super 35mm is nearly identical to the `Superscope 235'
process used in by RKO Pictures. The first film to use this format was
Run for the Sun in 1956. This was photographed using almost the same
frame area as Super 35mm, and then optically printed onto CinemaScope
(tm) release prints, leaving extra image area at the top and bottom of
the frame for TV prints.
35mm film frame: 35mm film frame:
(Academy ratio) (1.85:1 ratio)
(note inefficient use of negative space,
which is photographed in the camera,
but not projected)
| | | |
|O -------------------O| |O (unused space) O|
| | | | | ------------------- |
|O | Image |O| |O | Image |O|
| | | | | | Area | |
|O | Area |O| |O | |O|
| | | | | ------------------- |
|O -------------------O| |O (unused space) O|
| | | |
|<-------- 35mm -------->| |<-------- 35mm -------->|
super 35mm/silent film frame: 35mm anamorphic film frame:
| | | |
|O----------------------O| |O -------------------O|
| | | | | | | |
|O| Larger |O| |O | 'Squeezed' |O|
| | Image | | | | Image | |
|O| Area |O| |O | Area |O|
| | | | | | | |
|O----------------------O| |O -------------------O|
| | | |
|<-------- 35mm -------->| |<-------- 35mm -------->|
Vista Vision film frame:
-------------------------- ---
O O O O O O O O /|\
|--------------------| |
| Very Large | |
| | 35mm
| Image Area | |
|--------------------| |
O O O O O O O O \|/
-------------------------- ---
NOTE: The blank space to the left of the image area in the above diagrams
(except for Vista Vision and super 35mm) is reserved for a soundtrack
which is printed on release prints.
2.6 Which formats are common for 65mm cinematography?
-
5-perf 70mm camera frame: 2.066" x .906"
-
15-perf 70mm IMAX (tm) camera frame: 2.772" x 2.072"
2.6.1 65mm (standard 65mm theatrical frame)
The 65mm theatrical film frame is five perforations high (rather than
four for 35mm), and is capable of accepting a wider frame than 35mm
when photographed `flat.' While there have been attempts at fitting
anamorphic lenses onto 65mm cameras (such as `Ultra Panavision (tm)
70'/`MGM Camera 65 (tm) ,' most notably for the film Ben Hur, which
was originally presented in a 2.75:1 aspect ratio), none are presently
in use. While 65mm was once a popular shooting format, it is no longer
in wide usage, with the 1996 production of Kenneth Branagh's Hamlet
being the last major feature to use this film gauge.
It is hoped that the new digital sound formats will eliminate the
magnetic striping used in the past for soundtracks, which contributed
greatly to the cost of this format. Also, the potential exhibition
market for this format is larger than it has been in the past, since
many of the recently-built multiplex theaters have at least one screen
which is capable of showing 70mm, which was often originally installed
in order to show blowup prints of 35mm with the six-track stereo sound
which only the 70m print could provide (prior to the advent of
digital). The DTS digital format was successfully used for the 1996
70mm restoration prints of Vertigo (photographed in VistaVision). In
1997, several 70mm blowup prints of Titanic were struck from the super
35mm negative, also employing the DTS system.
65mm (IMAX (tm) /OMNIMAX (tm) )
The 65mm format is gaining popularity in the growing `ride film'
industry and for `special venue' production in various formats like
IMAX (tm) and IMAX DOME (tm) (formerly known as OMNIMAX (tm) ), which
use film frames of fifteen perforations wide. The film is run through
the camera and projector sideways, just like VistaVision, at fifteen
perforations of length per frame. IMAX (tm) has a projected aspect
ratio of about 1.43:1, but uses a very large screen to achieve its
effect. IMAX DOME (tm) /OMNIMAX (tm) films are shot with the same
cameras and lenses, but are projected onto a domed screen through a
fisheye lens. The screen itself is tilted somewhat toward the
audience, who sit in reclining chairs, arranged in a steeply-sloping
arrangement. Films photographed specifically for the domed screens use
wider lenses which help to reduce the distortion around the edges of
the screens.
There is a similar process to IMAX (tm) , known as IMAX-HD (tm) ,
which uses the same setup, running at 48 frames per second, in order
to achieve a more life-like, better-looking picture.
It is worth noting that none of the formats yet designed by the
Canadian IMAX (tm) company carries a soundtrack on the print. In older
setups, the sound is reproduced from a 35mm 6-track magnetic film
which is run on a dubber-type device, interlocked to the speed of the
projector (and if the power fluctuates significantly during a show,
sync is lost). Newer installations also have the capability of running
the sound off of a CD-ROM disk (as with DTS (tm) ), driven by a
tachometer output from the projector or a timecode on the film; even
when the sound is reproduced from CD, magnetic film is often still run
as a backup. A few films (such as Grand Canyon) used soundtracks
reproduced from 1/2" audio tape, using an 8-track recorder synched to
the projector.
65mm (SHOWSCAN (tm) )
SHOWSCAN (tm) is somewhat of a competitive format to IMAX (tm) and
IMAX-HD (tm) , conceived and supported primarily by Douglas Trumbull
and his Showscan Corporation. It uses 65mm film running vertically at
a rate of 60 frames per second (fps), five perforations per frame,
whereas standard IMAX (tm) , like almost every other format, runs at
24 fps. Supposedly this could give a clearer picture with fewer
`strobing'-type artifacts of the usual double-bladed shutter used for
35mm and standard 65mm (Showscan (tm) and IMAX-HD (tm) both use
projector shutters which show each image only once) and other
shortcomings of the 24 fps standard, in which the projector normally
shows each frame twice (using a double-bladed shutter, which makes one
revolution for each frame), which reduces apparent flicker somewhat.
Formats using the higher frame rate do not appear to flicker anyway,
and thus do not need this `fix.'
_________________________________________________________________
3 Motion Picture Formats (release prints intended for projection)
3.1 Which film gauges are currently in common usage for release prints intended
for projection?
Currently:
-
8mm (primarily amateur/low budget)
-
16mm (primarily nontheatrical)
-
35mm (theatrical)
-
70mm (theatrical/special-venue)
3.2 Why is wide-gauge film manufactured in the 65mm width for motion- picture
cameras, and in 70mm for release prints?
[under construction]
3.3 Which formats and aspect ratios are common for 8mm release prints?
-
standard regular 8mm projection frame: .172" x .129"
-
anamorphic regular 8mm projection frame: .172" x .129" (rare)
-
standard super 8mm projection frame: .209" x .156"
-
anamorphic 8mm projection frame: .209" x .156" (rare)
3.3.1 Regular 8mm/Super 8mm
Regular 8mm has a projected aspect ratio of 1.33:1, matching the 35mm
silent frame. Super 8mm has a similar projected aspect ratio of
1.34:1. Release prints in regular 8mm usually do not have a
soundtrack, although a few rare prints do. Super 8mm prints often have
a magnetic or optical soundtrack, located on the edge of the film
opposite the perforated edge. Films with magnetic sound also have a
`balance stripe' on the perforated edge in order to keep the film
thickness even, although sound is not normally recorded on it.
3.3.2 Regular 8mm/Super 8mm Anamorphic
Many 8mm reduction prints of 35mm anamorphic original films are
printed in a 2:1 squeeze ratio, which retains the original side
framing, but crops off a small portion of the top and bottom of the
frame. The final aspect ratios are 2.66:1 and 2.68:1 for regular 8mm
and super 8mm, respectively. Projection of these films, obviously,
requires an anamorphic lens for the projector in order to `unsqueeze'
the image. These lenses are, unfortunately, difficult to find, and
often expensive, despite their less-than-perfect image quality.
regular 8mm release print frame: super 8mm release print frame:
(note big perforations) (note small perforation)
| | | |
|s-------------- O | |s---------------- |
|o| Small | | | |o| Larger | |
|u| Image | | | |u| Image |o| <--- Smaller
|n| Area | | | |n| Area | | Perforation
|d-------------- O | |d---------------- |
| | | |
|<------ 8mm ----->| |<------ 8mm ----->|
3.4 Which formats and aspect ratios are common for 16mm release prints?
-
standard regular 16mm projection frame: .373" x .272"
-
anamorphic regular 16mm projection frame: .373" x .272"
-
super 16mm projection frame: .468" x .282"
-
1.85:1 super 16mm projection frame: .468" x .253"
3.4.1 Regular 16mm
When 16mm was first developed, 35mm silent films were shot for
projection in an aspect ratio (width to height ratio) of 1.33:1; thus,
the 16mm aspect ratio of 1.37:1 was designed to be relatively close to
the 35mm one. Unlike 35mm, however, no modification of aspect ratio
was needed in order to accommodate sound-on-film prints (the sound is
printed on one edge of the film, in the space formerly occupied by a
second set of sprocket holes [which are still present in todays
`double-perf' camera films]), and so the aspect ratio of 16mm remains
unchanged.
Unlike camera films, 16mm release prints are almost always single-
perforated-i.e. the film has perforations on only one side of the
image. The other side is reserved for a soundtrack. The only exception
to this are lab workprints from double-perf camera stock, which are
also printed on double-perf stock, mostly for convenience in splicing
with a `guillotine'-style tape splicer, commonly used by editors.
3.4.2 16mm Anamorphic
Although it is not a 16mm shooting format, 16mm reduction prints of
35mm anamorphic original films are often printed in a 2:1 squeeze
ratio, which retains the original side framing, but crops off a small
portion of the top and bottom of the frame. Projection of these films,
obviously, requires an anamorphic lens for the projector in order to
`unsqueeze' the image. Almost all 16mm anamorphic prints are
reductions from 35mm anamorphic originals.
3.4.3 Super 16mm
This is designed as a shooting format, and not for exhibition
purposes, but projectors are manufactured for this format, primarily
for the purpose of screening super 16mm dailies for a project which is
intended for television or 35mm blowup. Standard 16mm projectors can
also be modified for this purpose, by filing out the gate (a fairly
simple procedure). Most super 16mm projectors are found in laboratory
screening rooms or are owned by location rental houses. They are
almost never used for general film exhibition, except maybe for the
occasional film festival.
16mm release print frame:
| |
|sO--------------O |
|o| Image | |
|u| Area | |
|nO--------------O |
|d |
|<----- 16mm ----->|
3.5 Which formats and aspect ratios are common for 35mm release prints?
-
silent 35mm projection frame: .94" x .71"
-
Academy 35mm projection frame: .825" x .602"
-
1.66:1 European 35mm projection frame: .825" x .497"
-
1.75:1 35mm projection frame: .825" x .471" (obsolete)
-
1.85:1 US 35mm projection frame: .825" x .446"
-
anamorphic 35mm projection frame: .825" x .690" (current
standard)
3.5.1 35mm Silent Frame
In the early days of 35mm silent film, the standard aspect ratio was
1.33:1, and the image covered nearly the whole area of the film, four
perforations high, and extending out to the edges of the perforations
on the sides. These prints are almost extinct today, as they leave no
space for a soundtrack, and, thus, the format became obsolete upon the
introduction of sound on film in 1926. At this time, the frame was
simply narrowed, to the almost-square 1.15:1 ratio in order to
accommodate an optical soundtrack. This is the area used by the
current anamorphic format, and is the most image area one can fit onto
a piece of 35mm film with a soundtrack. As very few venues are
equipped to project silent-frame prints, this format is almost
non-existent today. Many silents have been re-printed such that the
image fits within the Academy frame.
3.5.2 35mm Academy Frame
When it became clear that nearly all future prints would contain
sound- tracks, the 35mm frame was cropped at the top and bottom
slightly in order to achieve a 1.37:1 frame, nearly matching the old
silent frame. This Academy frame is the basis for nearly all future
`flat' (non-anamorphic) formats, as well as the various television
formats currently in use.
3.5.3 35mm `Flat' Wide Screen Formats
With the introduction of CinemaScope (tm) in 1953 (see below), there
came a demand to release all films in a `wide' aspect ratio. This was
most easily achieved by cropping off the top and bottom of the Academy
frame in the projector. While most prints still contain the full
Academy frame-size image, the tops and bottoms of it are cropped off
in the projection process.
There are several commonly used formats which use this principle, of
which the most common currently is the U.S. standard of aspect ratio
1.85:1, used on almost all `flat' prints currently in circulation. One
of the major disadvantages of this format, however, is its terrific
inefficiency of negative space. Although the camera and projector both
move the film four perforations at a time (the height of the Academy
frame), the actual projected image only takes up 2.5 frames. Thus,
images are grainier and less sharp than those of Academy films
projected on the same height screen.
The proposed 2.5-perf and 3-perf formats (described elsewhere in this
FAQ) do not change the area of the 1.85:1 frame, but simply move the
film a shorter distance (2.5 or 3, rather than 4 perforations) between
frames, using less film per unit of running time. As proposed now,
these are strictly release-print formats; 35mm cameras will continue
to move the film 4 perforations per frame (although 3-perf is gaining
acceptance as an cheaper alternative for TV work).
A few films made in the 1950's were made to be projected in the 1.75:1
aspect ratio; while this is no longer a common projection ratio, it is
interesting now, because it corresponds very closely to the 1.77:1
proposed U.S. High Definition Television (HDTV) standard, designed as
a compromise in order to fit both 1.37:1 television material and wide
screen feature films onto the same size screen.
The standard frame ratio in Europe is still 1.66:1, the same as the
super 16mm standard. These films are almost never shown properly in
the U.S., however; most are simply cropped to fit onto screens masked
for 1.85:1.
3.5.4 35mm Anamorphic Frame
This frame is nearly the same size as the 1.15:1 frame used just after
the introduction of sound-on-film, and represents the most efficient
use of film area possible, while allowing space for a soundtrack. The
2.0x `unsqueeze' achieved during the projection of the film with an
anamorphic lens provides one of several aspect ratios, depending upon
the projector mask to be used.
The first CinemaScope (tm) (anamorphic) feature was The Robe, released
by Fox in 1953. These prints were made with tiny `Fox hole'
perforations, and contained four tracks of magnetic sound (quite
impressive, particularly in a time when most movie-goers had not even
heard regular stereo!). Due to the narrow perforations, an aspect
ratio of 2.55:1 was achieved for early Cinemascope (tm) pictures,
including The Robe, the first Cinemascope (tm) production.
In 1956, the 'scope ratio was narrowed to 2.35:1 in order to
accommodate both magnetic and optical tracks on the same print (so
that it could be shown in theaters not yet equipped with magnetic
sound equipment). This ratio was retained until 1971, when the height
was reduced slightly, resulting in a 2.39:1 aspect ratio, in order to
better hide lab splices.
In 1994, the height and width were reduced proportionally, retaining
the 2.39:1 aspect ratio, which is the current standard.
3.5.5 Projecting Multiple Formats
These formats are all standard, although each requires its own
projector mask (to cover up the unused image area) and lens (to ensure
that the image properly fits the screen). If necessary, the anamorphic
lens and mask can be used to show 1.37:1 Academy films, provided that
the anamorphic lens element is unscrewed and removed first, and the
curtains are adjusted to mask the 1.37:1 area (which will be very
small). Most theaters keep the top and bottom edges of the screen at
the same heights, and open curtains on either side of the screen in
order to accommodate the wider formats, as shown below (not to scale):
----------------------------------------
c) | | | | | | | | (c
u) | | | | | | | | (u
r) | | | | Movie | | | | (r
t) | | | | Screen | | | | (t
a) | | | | | | | | (a
i) | | | | | | | | (i
n) ---------------------------------------- (n
^ ^ ^ ^ ^ ^ ^ ^
| | | |----- 1.37:1 -----| | | |
| | |-------- 1.66:1 --------| | |
| |------------ 1.85:1 ------------| |
|----------------2.39:1 ---------------|
It should be noted that having separate lenses and masks for each
format is highly idealistic, and is not standard practice, except at a
few conscientious art houses, which must show prints from all time
periods and all countries. Most U.S. theaters are only equipped to
properly show 1.85 and 2.39:1 ratios, lacking the appropriate
lenses/masks and ability to move the curtains to other ratios. Thus,
when prints intended for other formats are shown, some of the image is
usually cropped. Some theaters show everything at 2:1 (eliminating the
need for changing the screen masking), cropping some from all formats.
In any event, there is a wide degree of variance in image cropping,
depending upon the equipment in place in each venue.
35mm release print frame:
(1.85:1 ratio)
(usually, picture is visible above and
below 1.85:1 framelines, but it is
35mm release print frame: masked off, and does not show up on
(Academy ratio) the screen)
| | | |
|O -------------------O| |O (unused space) O|
| s | | | | s ------------------- |
|O o | Image |O| |O o | Image |O|
| u | | | | u | Area | |
|O n | Area |O| |O n | |O|
| d | | | | d ------------------- |
|O -------------------O| |O (unused space) O|
| | | |
|<-------- 35mm -------->| |<-------- 35mm -------->|
3.6 Which formats and aspect ratios are common for 70mm release prints?
-
5-perf 70mm theatrical projection frame: 1.912" x .870"
3.6.1 70mm Standard Frame
The standard 70mm frame has always has an aspect ratio of 2.2:1, which
is slightly narrower than 35mm CinemaScope (tm) . Often, 70mm blowup
prints were made of 35mm CinemaScope (tm) films (mostly for the
improved sound quality of 6-track magnetic). These blowups are `flat,'
and often provide better image quality due to the superior
registration (image steadiness) of the 70mm format, as well as the
reduced grain imposed by the release print (more grains per square
foot of screen area). This was done more in the past (1970's through
1980's) because the high-quality six-track discrete (as opposed to
matrixed) soundtracks on 70mm prints could not be equaled by 35mm
optical Dolby Stereo (tm) tracks. Several innovations in 35mm,
however, most notably digital sound (along with Dolby (tm) SR, and
reverse-scanning solar cells) rendered 70mm blowups unnecessary if
sound is the only consideration. Further, the recent shift toward
10-20-screen multiplex theaters, and the resultant smaller screens,
has lessened the impact of the larger, better-quality image.
Much of the expense of making 70mm prints in the past has been the
magnetic striping which is necessary for the soundtrack, as there is
no such thing as 70mm optical sound. With the possibility of printing
a DTS (tm) timecode on the 70mm print, and providing the actual
soundtrack on DTS (tm) CD-ROM disks (like with 35mm DTS (tm) ), this
may no longer be necessary, possibly paving the way for a 70mm
revival. This remains to be seen, however, although it was done
successfully for the 70mm release of Hitchcock's Vertigo in October,
1996; the prints had no analog tracks and entire soundtrack was
reproduced from a DTS (tm) disk (most theaters used two disk readers
with identical disks in them for redundancy), driven by DTS (tm)
timecode printed on the outside edge of the perforations on the
left-hand side (relative to how the film runs in the projector) of the
image.
In addition to the conventional sprocket holes, all 70mm prints also
have a small `registration hole' punched every 5 perforations.
Theoretically, this is supposed to line up with the frameline, but, in
practice, this is ignored, and it just occurs at a random point. The
primary purpose served by the registration hole is for use as a
splicing reference, so that splices can always be made at the
frameline, even in the middle of a fadeout or a dark scene.
70mm IMAX (tm) /OMNIMAX (tm) 15-Perf Frame
These special formats are simple contact prints made from the
negatives (or intermediates). Although they are wider (by 5mm) than
the original negatives, they never contain a soundtrack printed
directly on the film. Sound is provided either by a separate,
interlocked magnetic tape, or by a CD-ROM disk, which is driven by a
timecode on the film (as in the DTS (tm) system used for 35mm digital
sound).
70mm standard release print frame:
(courtesy David Richards \texttt{daverich@netcom.com})
|XXoX|____________________________________|XoXX|
|XX X| |X XX| 'o' = sprocket hole
|XXoX| |XoXX|
|XX X| |X XX| 'X' = mag. track area
|XXoX| |XoXX|
|XX X| |X XX| (registration hole not
|XXoX| |XoXX| shown in this diagram)
|XX X| |X XX|
|XXoX|____________________________________|XoXX|
|XX X| |X XX|
|<---------------- 69.95mm ------------------->|
|<---------------- 2.754in ------------------->|
_________________________________________________________________
4 Motion Picture Sound Formats (release prints intended for projection)
4.1 What analog sound formats are common for 8mm release prints?
-
regular 8mm magnetic: 56 frame advance
-
super 8mm magnetic: 18 frame offset
-
super 8mm optical: 22 frame offset
4.1.1 Regular 8mm Magnetic (monophonic)
While regular 8mm was never designed to have a soundtrack, someone
figured out that the edge opposite the perforations could have a thin
magnetic stripe applied to it in order to carry a recording of film's
soundtrack. This, of course, uses the same principle as an ordinary
tape recorder. Unfortunately, though, this format was never
standardized, and never received wide usage. Complicating the issue
was the wide variety in the `sound offset'-i.e. the number of frames
ahead of the picture that the sound must run. If a film with an
18-frame sound offset were run in a projector which supported a
20-frame offset, then the sound would run slightly behind the picture.
Sound quality here is quite variable, depending upon the quality of
the striping job, the age of the print, and the quality of the
recording.
4.1.2 Regular 8mm Magnetic (monophonic or stereo)
Soon after super 8mm displaced regular 8mm as the standard home-movie
format, people began to demand sound capabilities for their cameras
and projectors. The easiest way to record sound while shooting is to
record the sound within the camera on a magnetic stripe pre-applied to
the edge of the film, in the same manner as the various regular 8mm
systems. A `balance stripe' is also applied on the sprocket-hole edge,
but not usually used for sound; its purpose is to maintain an even
film thickness. Aside from having two differing frame rates (18 fps
and 24 fps), this method became standardized for both cameras and
projectors, with a standard sync offset. Sound quality is potentially
quite good, with some recording devices and projectors offering stereo
reproduction by recording twin soundtracks, one on the `balance
stripe' and one on the regular sound stripe.
The primary disadvantage to this system of recording sound in the
camera is that it makes good editing extremely difficult. Super 8mm is
usually shot with reversal film (see below), meaning that the camera
original is edited and then projected. In this case, after every
splice, there will be a delay of about one second between when the
picture edit shows up on the screen, and when the sound edit is heard;
this is a result of the sync offset of the soundtrack. For this
reason, professional films (except old television news films) almost
never record sound within the camera, but rather use a `double-system'
method, in which the sound and picture are kept on separate strips of
film through the editing process, until the final release prints are
made. Home movies, though, rarely undergo substantial editing; thus,
`single-system' sound recorded in camera is useful and convenient.
4.1.3 Regular 8mm Optical (monophonic)
While magnetic sound is of high quality, it can be expensive,
particularly for large print runs. For this reason, optical
soundtracks, of the type used for 16mm and 35mm prints, eventually
found their way onto some 8mm films (usually, commercially released
ones). Only a few models of projector could reproduce this type of
soundtrack, however, and quality is less than desirable, due to both
the relatively slow linear speed at which the film moves past the
soundhead, and the inherent limitations of frequency response and
noise on an optical track (see description for 16mm optical for more
details).
4.2 What analog sound formats are common for 16mm release prints?
-
16mm optical: 26 frame offset
-
16mm magnetic: 28 frame offset
4.2.1 16mm Optical (monophonic)
The first sound-on-film 16mm prints, made in the 1940's, used an
optical system, like that used on the 35mm prints of the time. An
optical track consists of an image of a `wave'-like clear band which
allows differing amounts of light to pass through it upon playback
(this is called a `variable area soundtrack'; `variable density
soundtracks' were also tried at one time-they did not use a band of
clear film, but rather the entire soundtrack area varied in density,
or transparency. This gave a slightly better frequency response than a
variable-area track, but resulted in increased background noise, due
to film grain. They are no longer used). The sound is reproduced by
means of an exciter lamp, which shines through a small lens onto the
optical track area of the film. This light is focused onto a solar
cell on the opposite side of the film. The solar cell varies its
electrical resistance based upon the amount of light which is shining
on it. Thus, as the `wavy' band gets wider, more current can pass
through the solar cell, which causes the loudspeaker to vibrate more,
which results in a louder sound. This system is rather primitive, but
it is inexpensive, as the sound is printed on the film at the same
time as the picture, whereas magnetic systems require a separate
`sounding' step after the picture is printed.
Sound quality is not particularly good, but has been improved in
recent years by various methods, including the printing of two
identical tracks which are adjacent to each other. This method allows
the two tracks to cancel out each other's flaws or at least to cover
them up (in theory). Whether or not this actually improves sounds
quality is a topic of debate. Thus, Although it is technically
possible to produce a stereo optical track in 16mm, no one has yet
exploited this potential on a wide-scale basis, as there is no
commonly available equipment to shoot a stereo track, or to reproduce
it. A few test prints were made in this format, however.
4.2.2 16mm Magnetic (monophonic)
In an attempt to improve the sound quality for 16mm prints, magnetic
sound was developed in the early 1960's. This, like 8mm magnetic, used
a magnetic stripe which was placed in the same location as the optical
track (or slightly to the outer edge, if both types of tracks were to
be used on a single print). The problem with this system was that,
while it sounds quite good, few projectors are capable of reproducing
it. Thus, its use was pretty much reserved for television news (until
the late 1970's, when news film was replaced by videotape); news
cameras, such as the Auricon and the CP-16, were modified to record
magnetic sound directly onto pre-striped reversal stock. This film was
developed at TV stations, and was then run through a `magnetic offset
recorder,' which simultaneously played the soundtrack, and re-recorded
it 28 frames earlier, so that the film could be edited with the sound
in perfect sync. The film was again run through the offset recorder,
this time to re-advance the soundtrack 28 frames after the picture so
that it could be played back in sync on the station's film chain
machine. This was the solution to the sync problem common with super
8mm films with recorded-in-camera-sound.
By now (1998), 16mm magnetic is almost a dead format for new prints,
having been replaced with 35mm blowups of 16mm-originated material or
by double-system digital systems (usually with a DAT machine synched
to the movie projector).
4.3 What analog sound formats are common for 35mm release prints?
-
optical (20 frame offset) - 35mm
-
magnetic (?? frame offset) - 35mm
35mm Optical (monophonic, stereo, or Dolby Stereo (tm) )
The standard sound-on-film system for 35mm has always been optical
sound. This works like the variable-area system described above under
`16mm optical.' This system is inexpensive and standardized, so that
almost every projection setup in the world is capable of reproducing
it. Of course, the disadvantages are as with any optical sound system:
lousy frequency response, noise, and `pops' when splices pass through
the soundhead.
Eventually, in the 1970's, the standard monophonic track was modified
to permit stereo reproduction. This allowed optical tracks to offer
competition to the four-track magnetic systems in use at the time. The
reproduction of stereo tracks required modification of the projector's
soundhead to accept a stereo solar cell. The optical stereo approach
was not used commercially, however, due to background noise and hiss
issues. In the mid-1970's, Dolby (tm) Laboratories developed methods
of `matrixing' the SVA (stereo variable area) track in order to encode
four tracks worth of information within the twin stereo tracks. This
allowed for the additions of a center (dialogue) track and a rear
`surround' track to the usual left and right stereo tracks. In
addition, Dolby (tm) type `A' noise reduction was used to reduce
background noise.
This `Dolby Stereo (tm) ' system soon became standard, and nearly all
commercially released films since about 1980 have been encoded with
it. Of course, one must use a Dolby (tm) Cinema Processor (or a clone
thereof [e.g. `Ultra Stereo']) in order to decode and reproduce all
four tracks; otherwise, it just reproduces as two-track stereo. `DTS
Stereo (tm) ' uses the same principles as Dolby Stereo (tm) and is
decoded with the same equipment, but the term applies to optical
tracks produced by DTS (tm) , without the use of Dolby (tm) equipment
(Dolby (tm) encoding equipment is usually rented out for higher
rates). Note that `DTS Stereo (tm) ' is distinct from the DTS (tm)
digital sound system described below.
In the late 1980's Dolby Stereo (tm) was improved upon by `Dolby SR
(tm) .' The `SR' stands for `spectral recording,' which incorporated
better channel separation and noise reduction than standard Dolby
Stereo (tm) , but which supposedly retained compatibility with Dolby
(tm) type `A' processors, although this is debatable. A Dolby (tm) `A'
processor can be upgraded to support SR prints, if desired. Type `A'
prints do not reproduce well when played back through a processor set
up for `SR' mode (all modern processors also contain the `A' NR mode
as well).
Incidentally, Dolby (tm) `A' noise reduction is one of several noise
reduction schemes developed by Dolby (tm) Laboratories. It (and SR)
are capable of reducing noise across the entire audible frequency
range. Dolby (tm) also developed type `B' noise reduction, which
reduces the high- frequency noise common to audio cassette tapes, and
type `C' noise reduction which is also used for cassettes, as well as
the Beta SP videotape format.
4.3.2 35mm Magnetic (four-track stereo)
When the first CinemaScope (tm) films were produced, Fox had special
release print stock made up, which contained very narrow perforations
(known as `Fox holes'). The idea behind this was to allow for a
magnetic sound- track containing four discrete (not matrixed) tracks
(in the same L/C/R/S configuration as the modern Dolby Stereo (tm)
setups). At the time, the 'scope image was wider than it is now
(because it extended into the area now used for optical tracks), and
thus could not fit an optical track on the print. The magnetic stripes
were applied in the same manner as to 70mm prints.
This idea worked reasonably well, and was used for a number of years
(through the early 1970's) on 35mm prints of all formats (only 'scope
prints required the Fox holes, though), and the sound quality was
excellent, even by today's standards, provided that the magnetic
tracks were in good condition. The problem of this scheme was that,
unlike optical sound, the information recorded on magnetic tracks was
not a permanent part of the film, and could be intentionally or
accidentally erased, simply by being placed too close to magnetic
fields, like those found in electric motors (such as those used on
rewind benches). Even reels and cans can become magnetized, sometimes
erasing all or part of the magnetic track, requiring that it be
re-dubbed, at great expense. Further, the magnetic sound heads
required frequent cleaning in order to keep them sounding good.
With the invention of Dolby (tm) `A' noise reduction and the
application of this technology to optical tracks, magnetic sound lost
some of its quality advantage over optical, and it has always been
substantially more expensive than optical to print (as prints had to
be dubbed in real time, whereas optical could be printed at the same
time and speed as the picture). Thus, magnetic sound fell into disuse,
and is no longer commonly used, although, before digital sound became
workable, special prints were made with magnetic tracks for showing in
select theaters for `special engagements' and the like.
4.4 What analog sound formats are common for 70mm release prints?
-
magnetic (?? frame offset) - 70mm
4.4.1 70mm Magnetic (six-track stereo)
This system is capable of carrying six separate tracks on four wide
magnetic stripes on the film. It is usually set up to reproduce left,
left-center, center, right-center, right, and surround tracks. This
was long considered to be the premier film-sound format, prior to the
advent of digital, because the tracks were relatively wide, because
the film runs through the projector at a slightly higher rate of
linear speed than 35mm film, and because the sound is recorded in
discrete (separate) tracks, rather than being `matrixed.'
As mentioned above, in the late 1970's (beginning with Star Wars)
through the late 1980's, it was common for distributors to produce
70mm blowup prints of films shot on 35mm in order to improve sound
reproduction in the movie theater. With the introduction of digital
systems, which are capable of reproducing higher quality sound at a
lower cost than a complete 70mm projection system and 70mm print
rental, exhibitors no longer saw much reason to show blowup prints,
except for special `one-time' shows. In the future, magnetic striping
(a major cost of making 70mm prints) may be eliminated, in favor of a
digital soundtrack (currently, DTS (tm) has been used for 70mm
prints). This may encourage the printing (and 65mm original
cinematography) of more films for 70mm exhibition.
Unlike other formats, where the soundtrack runs ahead of the picture,
with 70mm, the sound runs behind the picture, as the magnetic sound
heads are placed before the picture head. Thus, the 70mm print runs
through the magnetic soundhead, picture head, then around the 35mm
optical soundhead, then to the takeup reel or platter. When 35mm films
are run in a combination projector, they are simply loaded through the
70mm magnetic soundhead, without difficulty.
4.5 What are the three commonly used digital sound formats for 35mm release
prints, and how do they work?
4.5.1 General Information
-
Digital Theater Systems (DTS (tm) )
-
Sony Dynamic Digital Stereo (SDDS (tm) )
-
Dolby (tm) Digital (SR-D (tm) )
Digital sound differs from analog sound in that it represents sound by
a series of consecutive `samples' of the sound (each of which is
represented by the digits zero [0] and one [1]), rather than by a
continuous waveform. Digital is neither inherently better nor
inherently worse than analog, but simply a different method of
representing sound (music, dialogue, etc.). In practice, though,
digital film sound almost always sounds cleaner and brighter than
analog, and is capable of greater dynamic range, due to the
limitations of the optical track as a means of recording sound.
Despite the differences among the various digital sound formats, most
people cannot tell a difference in quality, as they all sound
excellent. Perceived differences among the formats are usually a
result of a different sound mix for each format (such as an 8-channel
SDDS (tm) mix versus a six-channel Dolby (tm) Digital mix).
Digital Theater Systems (DTS) (tm)
This was the first digital sound system to come into widespread usage,
with the release of Jurassic Park in 1993. The system was promoted
heavily by MCA/Universal Pictures, which uses it on most of its
prints. The system originally was sold in two versions: a low-end
version which could reproduce four tracks, and a high-end version
capable of reproducing six- tracks (left, center, right,
left-surround, right-surround, and subwoofer. These systems were
referred to as DTS-4 (tm) and DTS-6 (tm) , respectively. The
four-track version has since been discontinued.
DTS (tm) uses a timecode printed on the film between the picture area
and the optical track. The timecode, which looks like a dot-dash
pattern resembling Morse code) is read by an optical reader placed in
the film path, between the platter or reel and the projector's picture
head. This timecode information is fed to a specialized, souped-up 386
or 486 computer which in turn reads compressed soundtracks from a
CD-ROM disk; the compression factor, though, is the least of the three
digital systems. The current systems have three separate CD-ROM
drives: one holds a `trailer' disk which is sent to theaters
periodically, and contains the soundtracks to all of the trailers
currently showing, including trailers from studios which do not use
DTS (tm) for their films; the other two contain disks for the feature.
Shorter movies require only one disk; others require two. Slightly
over four hours of digital sound can be accommodated for a two-disk
feature. There is no provision for mid-show disk changes.
As with all digital sound systems, the film reader can be placed a
variable number of frames ahead of the picture head. This is
calibrated upon installation with a test film. The computer is capable
of accommodating splices within the film, and adjusting the soundtrack
to match. Further, because the soundtrack is not on the film, no
`popping' noise is heard during splices and/or changeovers (unless the
timecode reader cannot read a certain section of timecode, in which
case it reverts back to the standard analog track, causing a small
`pop').
As with all of the current 35mm digital systems, all prints (except
70mm DTS prints) contain a standard optical track (usually recorded in
`DTS Stereo (tm) ,' a system which is compatible with Dolby (tm) -type
processors) as a backup, should the timecode not be found, or be
unreadable for more than 40 frames. The analog track is also used when
the CD-ROM disk does not match with the movie being shown (at least in
theory-there have been reports of theaters' showing one movie with
another's soundtrack).
Sony Dynamic Digital Stereo (SDDS) (tm)
Sony has entered the cinema sound market with the SDDS (tm) system.
Unlike the other two digital systems, SDDS (tm) is capable of
reproducing eight tracks of sound (left, center, right, left-center,
right-center, left-surround, right-surround, and subwoofer),
potentially a great advantage for films mixed for eight tracks, as a
small number are at present. This, of course, requires that theaters
install additional loudspeakers (left-center and right-center) behind
the screen in order to take advantage of the potential of this format,
however.
In SDDS (tm) , the sound is actually recorded on the film itself,
along both edges of the print. SDDS (tm) uses a middle level of
compression of the digital information of the three current digital
systems. Like the other digital systems (except for Dolby), the reader
(which uses an LED to shine through the track) is placed somewhere in
the film path prior to the film's entrance into the picture head (the
offset is variable, as convenience dictates, and is set up at
installation). The reader reads the track, which is then decoded,
decompressed, and processed in a separate processor unit, which
contains custom electronics designed for this purpose. Just as with
analog sound, splices are accommodated without difficulty.
SDDS (tm) is probably the most expensive of the three digital formats,
although actual cost varies substantially among different theaters and
chains. The expense is largely due to the fact that all of the
electronics within the entire processing system are digital, whereas
DTS (tm) and Dolby (tm) Digital are both designed to simply be plugged
into existing analog Dolby (tm) (or similar) cinema processors.
However, the extra cost may be somewhat justified by the extra tracks
and the fact that the marketer of this system also owns companies
which produce many films each year, almost ensuring that there will be
material in this format for many years to come.
Although it is expensive, SDDS (tm) is very popular, particularly in
the AMC, Sony, and United Artists theaters, where SDDS (tm) is or will
be used in most of the theaters. Many technicians like it because it
is the only system with electronic equalization, allowing the system
to be properly set up very quickly.
Dolby (tm) Spectral Recording Digital (SR-D) (tm)
Dolby (tm) Digital, also known as SR-D (when an SR track is used for
the analog backup), is the digital system from Dolby (tm)
Laboratories. Like DTS (tm) , it is capable of reproducing six tracks
(left, center, right, left-surround, right-surround, and subwoofer),
which are read by a reader (which works much like a TV/video camera,
capturing images of the track) placed before the picture head, or, in
some installations, within the standard projector soundhead. Like the
other two systems, the offset can be varied, and is calibrated at
installation. The actual soundtrack on the film runs 26 frames ahead
of the picture.
The actual digital sound information is printed on the film in between
the perforations, generally considered to be a safer location for the
sound information than the edge of the film (where SDDS's (tm) track
lives). Thus, Dolby (tm) Digital is potentially more reliable than
SDDS (tm) , although it compresses the digital information to a lesser
extent than SDDS (tm) does. Like SDDS (tm) , the track is read, and
then decoded, decompressed, and processed by a separate unit. Splices
can create small `pops,' (and will revert to analog if more than five
perforations are obscured, but this is unlikely..
This format appears to be increasing in popularity at this time, both
in terms of the number of theaters installing the system and the
number of prints available in that format. It is also considered to be
slightly more reliable than the other two digital formats, as the
sound is printed directly onto the film in a relatively `protected'
location. All prints still contain an analog optical track (usually
recorded in Dolby (tm) SR), in case the digital system fails, or is
unable to read five consecutive `blocks' (between perforations).
Technically, it is possible to, with minimal cost, print all three
types of digital track (or, in the case of DTS (tm) , timecode), along
with analog optical Dolby (tm) on a single print, and a few films have
been printed this way. These multi-format prints are now quite common
(containing at least two formats), especially on movie trailers.
Similarly, it is possible to have a projection system which can
accommodate all of these formats, without excessive difficulty.
4.6 What methods have been used for digital sound in formats other than 35mm?
[under construction]
As mentioned in the 70mm section, DTS (tm) timecode has been printed
on 70mm prints (most notably the 1996 restoration prints of Vertigo),
and used to drive a DTS (tm) CD-ROM disk, from which sound was
reproduced as with the 35mm implemetation of DTS (tm) . A standard DTS
(tm) setup is required for this type of system, as well as 70mm
timecode readers (which are swapped in for the 35mm variety as
needed), and, often, a second DTS (tm) CD unit, which holds a
duplicate set of CDs and provides a backup should the first unit fail.
As of February, 1998, there is no indication as to whether Dolby (tm)
or Sony (tm) were planning to adapt their 35mm digital systems for use
with 70mm.
_________________________________________________________________
5 Motion Picture Presentation (theatrical projection)
5.1 What type of projection and sound equipment is commonly used for commercial
theatrical presentation?
5.1.1 Projector/Lamphouse
The projector is the most critical part of any theater's projection
setup. Many newly installed theaters in the US use new or rebuilt
Simplex or Century 35mm projectors. The most common Simplex models are
the Simplex XL (a.k.a. Pro 35, a currently manufactured model), the
older Simplex E-7, and the really old Super Simplex. The most common
Century models are the SA, the older C, and the 35/70mm JJ.
Larger theaters built from the 1960's through the 1980's may instead
be using combination 35/70mm projectors, like the Norelco AA-II (known
in Europe as the Philips DP-70), and Century JJ, although, with the
decreased availability of 70mm features of late, most of these
machines are either used exclusively for 35mm shows or are sitting
idle.
Most modern theaters use xenon bulb lamphouses of between 2 and 4
kilowatts. This provides a picture of adequate brightness on the
medium-sized screen common in multi-screen cinemas. A larger lamphouse
of up to 5-7 kilowatts is needed for a very large screen, such as that
of a drive-in theater; larger lamphouses offer little increased
benefit for 35mm. Older theaters often still use carbon-arc lamps,
which require more attention on the part of the projectionist than
xenon, but some feel that they offer a light of better color
temperature (i.e. not as cold-looking) than xenon. The general rule of
thumb for xenon lamphouse size is roughly 1kw of power for every ten
feet of screen width; thus a 30-foot screen should require about a 3kw
lamphouse.
As for the film handling system itself, automated cinemas usually use
film `platters,' in which the entire print is loaded onto a large
plate-like device (with the film from the individual shipping reels
spliced together into one continuous roll), permitting one
projectionist to operate the projection equipment for many auditoria.
Smaller theaters and older theaters often use two projectors with
small reels, each holding either 2000' each (just like the shipping
reels) or 4000-6000' each (with the contents of two or three shipping
reels spliced together). Between the reels, the projectionist operates
a changeover mechanism, simultaneously switching over machines and
soundtracks. He then rewinds the next reel, reloads it on the idle
projector and prepares for the next changeover.
5.1.2 Sound System
The sound system in a typical mid-size theater installation is capable
of handling from 200-400 watts of power for the front channels. In a
mono system, several loudspeakers are located behind the screen,
reproducing a single channel of sound. A Dolby Stereo (tm) or other
multichannel system involves at least three loudspeakers behind the
screen to reproduce the front channels, as well as several
loudspeakers along the side and rear walls of the auditorium to
reproduce the `surround' channel of sound. The soundtrack itself is
read from the film by a solar cell arrangement within a soundhead,
commonly a Simplex SH-1000 or similar.
Typical Multi-Track Dolby (tm) Stereo/Dolby (tm) Digital/DTS setup:
(This is the same setup used for Dolby (tm) Stereo, DTS (tm) , and
Dolby (tm) Digital setups, although the digital systems have separate
L and R surround channels, as well as a channel for a subwoofer [which
is located behind the screen]. Complete SDDS systems and 70mm also
have Left Center [LC] and Right Center [RC] loudspeakers, not
indicated here)
Left Stereo (L) -- behind left side of screen
Right Stereo (R) -- behind right side of screen
Center/Dialogue (C) -- behind center of screen
Surround (S) -- in rear of auditorium (separate L/R in digital)
Subwoofer (sub) -- behind screen (separate channel for digital)
/----------------------------------------------------------\
| * L * * C * * R * |
| * spkr * (sub) * spkr * * spkr * |
| ------------------- screen ------------------- |
| |
| (front of auditorium) |
| |
| UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU |
| UUUUUUU UUUUUUU audience UUUUUUU UUUUUUU |
| UUUUUUU UUUUU seating area UUUUU UUUUUUU |
| UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU |
| UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU |
\ \
/ /
\ \
|* S * UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU * S *|
|*spkr* UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU *spkr*|
| UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU |
| UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU |
|* S * UUUUUUU UUUUUUUUUUUUUUUUUUUUUUUU UUUUUUU * S *|
|*spkr* *spkr*|
| * S * * S * |
| *spkr* (rear of auditorium) *spkr* |
\----------------------------------------------------------/
Digital sound systems use similar loudspeaker arrangements as Dolby
Stereo (tm) setups, possibly with additional loudspeakers to support
SDDS (tm) eight-channel mixes. The sound is read by specialized
readers placed between the reels/platters and the projector head; this
contrasts with the placement of the analog soundhead, which is located
between the projector head and the take-up reel/platter.
5.2 What are some specific examples of a common projection setup?
[under construction]
5.3 What are the differences between xenon, and carbon-arc lamphouses?
Most commercial theaters currently employ xenon bulbs; these are glass
tubes containing a highly pressurized xenon gas through which high
electrical current is passed (usually 220V, 50 amps or higher). They
typically last for several thousand hours prior to needing
replacement. Aside from being rotated and changed at regular intervals
(they start to flicker as they get old), xenon lamphouses need very
little maintenence (unless the bulb explodes due to the high pressure
inside the bulb, in which case the rear reflector in the lamphouse
must be re-silvered). Bulb glass tends to weaken as it ages, and thus
extreme care should be taken when replacing bulbs to ensure that the
bulb does not explode.
Older installations may use or have once used carbon-arc lamphouses;
in these setups, high electrical current is passed between two carbon
rods (one positive and one negative), creating an electrical arc and a
very bright flame in the gap between the two rods. In order to operate
such a lamphouse, the projectionist inserts the rods into their steel
holders, closes the lamphouse, switches on the power, and, watching
through a shielded piece of glass, carefully brings the rods together
(using positioning knobs on the side of the lamphouse), causing them
to touch. At this point, the arc will strike, and he can bring the
rods apart and allow the current to stabilize. As the carbon burns
down during the show, a motor brings the rods together, maintaining a
constant distance between the tips of the rods, which must be tweaked
by the projectionist as the show goes on, in order to maintian
consistant on-screen light. Every 30 minutes to an hour of use, the
rods will burn down and must be replaced.
Separate rods are used for `positive' and `negative' poles; a longer,
thinner one is placed in the positive holder, and a shorter, fatter
one is used for the negative holder. These designations should be
marked on the box of carbon rods. Fumes from carbon-arc lamphouses are
highly noxious, and should be well ventilated.
Note that both xenon and carbon-arc lamphouses require DC power,
provided either by DC mains or by a rectifier circuit (which converts
standard AC power to DC). Older theaters may use motor-generator sets
to generate DC power.
5.4 How are `seamless' manual reel changeovers accomplished?
5.4.1 Shipping Configurations for 35mm Prints
Nearly all 35mm prints are shipped on metal reels which hold 2000' of
film. Ideally, the films are shipped `tails out,' meaning that the
beginning of the film is at the middle core of the first reel, and the
end is at the outer edge of the last reel. These reels are shipped in
so-called `S-wind,' meaning that the emulsion (dull side) winds facing
`in' when the `tail' is `out,' and that, when rewound, the `head'
should face `out,' and the emulsion will wind `out.' This confusing
standard is designed to help prevent print damage, although there are
conflicting views on this. When the film runs through the projector,
the top reel spins counterclockwise, and the lower reel spins
clockwise.
At some undetermined time, new prints are likely to be shipped on the
so-called Extended Length Reel (ELR), which is capable of holding
6800' of standard triacetate film or 8000' of the thinner polyester
stock. Trials of this began in Summer 1997, with prints of Addicted to
Love and Batman and Robin. These prints were also available on 2000'
reels for theaters which requested them. This is expected to reduce
the amount of time needed to build up a print on platters, and
possibly reduce the damage done in the buildup/breakdown process. This
standard is supported primarily by the exhibitors (who will save in
labor costs) and film laboratories (although some will need to buy new
equipment to handle the larger reel sizes). Presumably, at least for a
certain amount of time, 2000' reel sizes will also be distributed for
these films, in order to accommodate theaters which do not have
platters or 6000' reel arms, and must instead run the films with 2000'
reels. Eventually, these houses may have to convert to 6000'
changeover or platters or cut up the ELR prints themselves.
It should be noted, also, that nitrate prints have sometimes been
shipped on 1000' reels, due to fire-hazard concerns. This
configuration presents less of a danger, should one reel catch fire,
as there is less film to burn. These nitrate films also are usually
stored on metal shelving, in asbestos-insulated fire-proof rooms.
Modern triacetate or polyester films, of course, do not require these
precautions.
When the film arrives at a changeover house, the head projectionist
rewinds the film onto cast-iron house reels, inspecting the print for
damage and splices, as well as (hopefully) ensuring that the
changeover cue marks are properly positioned: 4 frames "motor" cue,
then 10 ft. 8 frames, then 4 frames "changeover cue" then 20 more
frames.
5.4.2 Changeover Procedures
Just before the show starts, the first (house) reel is loaded in one
projector and the second reel is loaded into the other. The first
projector is started; a few minutes before the first reel ends, the
projectionist then stands before the second machine, looking out at
the screen, waiting for the first cue mark (a small dot in the
upper-right-hand corner of the picture for four consecutive frames
[made by punching holes into the internegative; they appear round on
`flat' prints and, due to the `unsqueeze,' elliptical on scope
prints]). Upon seeing this, he hits a button on the changeover
controller, striking the lamp (if this is the first changeover;
otherwise, the lamp (if xenon) will have already been struck, and will
probably not be turned off until the end of the show; this avoids
excessive thermal stress, which causes bulbs to explode, and avoids
the embarrassment of having the bulb blow up when first struck, right
before a changeover), and starting the motor on the second machine.
The second reel has, hopefully been loaded up properly in the second
machine, with the framelines lined up with the top and bottom edges of
the gate (if this is not done, the film will probably appear out of
frame, and the projectionist will have to manually adjust the
projector's `framing' knob in order to position the picture correctly
on the screen. Two types of leader are currently found on release
prints. New SMPTE Universal Leader is marked off in seconds of time
(considered to be more useful for television stations), and counts
down from `8' to `2'. This is used on nearly all new prints. Older
Academy Leader is marked off in feet of film, counting from `11' to
`3,' and is common on older prints. The projectionist simply remembers
which frame of each type of leader needs to be loaded into the
projector in order to give the correct `run-up' time between cue
marks. If the leader is not complete and the projectionist is not able
or willing to replace it, he must wait after the first cue mark
(before starting the motor on the second machine) until roughly where
the next reel was loaded.
Once the second projector is going, the projectionist waits for a
second dot, located 20 frames from the end of the first reel. Within a
half-second or so after seeing this, he hits another button, which
switches over the soundtrack, and simultaneously opens (on the machine
holding the second reel) and closes (on the machine holding the first
reel) a metal `changeover' blade, which allows the passage of light
through the film and, of course, onto the screen. The first reel is
either stored in the film's metal shipping case, or rewound back onto
a house reel on a rewind bench. The process is repeated for every reel
change.
5.5 How does a platter system work?
5.5.1 Platter Configurations
Platter systems are used commonly in `automated' booths, allowing one
projectionist to run several shows (such as in a multi-screen theater)
simultaneously by eliminating the need for manual changeovers and the
rewinding of reels. The platter itself is a large, flat, circular,
metal table, mounted on a column of like plates, on which the film is
wound, tails out, with the shipping reels all spliced together.
Platters are usually installed in stacks of three, allowing two films
to be ready to run at any one time, along with a takeup platter for
either. This setup also allows one print to be made up/broken down
while another is running.
5.5.2 Platter Operation
After the print is spliced together, soundtrack edge facing up, the
projectionist removes the metal core, (a.k.a. the `donut') around
which the film is wound `tails out', from the center of the platter,
loads the film across a series of rollers and through the projector,
and attaches the donut to an empty platter. The film feeds out the
center of the first platter, and is taken up on the second one. In
this way, a show may be started, and, as long as no problems occur,
run through its end without continual supervision. Because the film is
taken up with the head at the center of the platter, there is no
rewinding necessary. To run the same film again, the film is fed from
its current platter onto another empty one. This can potentially save
time by eliminating the rewind stage, allowing the same show to be run
almost continuously.
So-called `endless loop platters' also exist, and work similarly,
although they omit the donut, and instead require that the head and
tail be spliced together, allowing the same film to be run multiple
times with no interruptions. Unfortunately, though, these systems
discourage the cleaning of the projector gate, and, as dust and dirt
accumulate there (an inevitable result of showing films), can lead to
print scratches and other damage.
After building up a print on a platter, it is good practice for the
projectionist to run it once in order to preview the print for any
problems which may have been introduced in print buildup (like bad
splices) and other defects, which may have been introduced elsewhere
(like deep scratches, or lousy lab work). Splices used to build up
prints on platters are usually made with `zebra' tape, which has
yellow markings which help the projectionist to locate the splices
when breaking down the print onto the shipping reels.
5.6 How are multiple projectors interlocked to run the same piece of film in
multiple auditoria?
(information courtesy David Richards daverich@netcom.com)
This is occasionally done in multiple-screen theaters; the projectors
which are going to be interlocked need to be adjacent to each other
(or at least reasonably close), and must be fitted with synchronous
motors, whose speed is controlled by the 60hz (in the U.S.; 50hz in
many other countries) AC line frequency. The film is loaded from a
platter through the first projector (as usual), and then passes over
several rollers, mounted on a wall or ceiling, across the booth to the
second projector, into which it is then also loaded normally.
Somewhere between the two machines, there is usually a bit of slack in
the film, where a weighted roller is placed in order to keep the film
running smoothly if there happens to be a small speed variation during
the show.
Both projectors must be started at exactly the same time in order to
maintain the proper amount of slack between them. This is done either
by two projectionists, or by an automation system capable of handling
this function.
It should be noted that the term `interlocked' is also commonly used
in the context of a sound mix facility, where several magnetic
dubbers, and, usually, a projector, must be mechanically or
electronically interlocked together in order to ensure that the
multiple soundtracks being mixed are in perfect sync with each other
and with the workprint being projected.
5.7 What are the industry standards for image brightness and screen
reflectivity?
According to the Society of Motion Picture and Television Engineers
(SMPTE), the generally accepted standard-setting organization for the
industry, films are to be projected at a brightness level of 16
footlamberts (+/- 2 footlamberts). There is no standard for screen
gain, and it varies substantially from theater to theater (from 1x to
3x is common). Screen gain deteriorates over time, and thus requires
that screens be replaced periodically.
5.8 What are the industry standards for sound levels in a mono setup?
[under construction]
What are the industry standards for sound levels in a Dolby Stereo (tm) setup?
This is widely ignored, but officially, a CAT-85 pink noise generator
card in a Dolby processor should generate a sound level of 85 decibels
at the `average' seat, and this should be calibrated to the `7' on the
volume dial (which ranges from 1 through 10). Mixing stages are set up
in this way, although theaters are often calibrated for lower sound
levels, as films (and, more frequently, trailers) sometimes get mixed
too loud.
5.10 How does a dual-format (35/70) projector work, and how is the changeover
made between formats?
(courtesy David Richards daverich@netcom.com)
These comments apply to the Century projector. There are two
significant differences between a 35/70 projector and a standard 35mm
projector. First of all, it must acommodate two gauges (widths) of
film. This mainly impacts the gate. Typically, the gate is easily
removable. Whereas the 35mm projector is restricted to accepting a
35mm gate, the 35/70 projector comes with two gates, one for each
gauge of film. These gates are precision machined to slide onto
dovetails on the frame, and should not be interchanged between
projectors. The gates are stamped with the frame serial number to
prevent mix-ups.
The second difference is the frame pitch. Standard frame pitch for
35mm film is 4 perforations, or .748". 70mm film uses the same
perforation pitch, but 5 perfs per frame, or .935". Both must advance
at 24 frames per sec. There are two possible ways to accomodate the
faster linear speed of 70mm. One would be to simply turn the sprockets
faster, with gearing for example. But this would not work with the
existing geneva movement, and would also throw the shutter timing off.
The way it is actually ac- complished is by using dual sprockets.
There are 3 critical sprockets: the upper feed sprocket, which pulls
film off the reel or platter at a constant speed, the intermittent
sprocket, which advances the film at the gate, and the lower sprocket,
which smooths out the pulsations from the intermittent sprocket once
again. There are additional sprockets in the area of the sound head,
but they do not need to be used for 70mm, as there is a separate
magnetic sound reader for that.
Typically, these sprockets have 16 teeth for 35mm film. Since one
frame is 4 perfs, exactly 4 frames could be wrapped around each
sprocket. Another way of saying this is that each sprocket turns 90
degrees per frame. Since 70mm film requires a 5-perf advance, we can
simply increase the number of sprocket teeth by 5/4, to 20 teeth, and
the speed and intermittent advance distance are increased exactly the
right amount, without changing the Geneva movement, motor, or anything
else. By a happy coincidence, the 70mm film requires both a larger
diameter sprocket, and one with the two sets of teeth further apart to
accommodate the greater width. So, by using stepped sprockets, both
may co-reside on the same shaft. The 35mm film rides in-between the
larger 70mm sprocket flanges.
The only thing remaining is the pads that hold the film against the
sprocket. Since there are two different sprocket diameters, there are
two different places the pads must stop. This is accomplished on the
Century with two different diameter pad rollers, which rotate
individually, the assembly of both of them revolves on a common shaft
with a knob. By turning the knob one way, the 35mm pad roller comes
against the film. By turning the knob the other way, the 70mm pad
roller comes against the film. With 35mm film threaded on the machine,
turning the knob the wrong way does no damage, however, the film will
not be held securely against the sprocket. With 70mm film threaded,
care must be taken, because turning the knob the wrong way will damage
the print.
This combination 35/70 idea, while good in theory, has some drawbacks
in practice. Even with everything set correctly for 70mm, it is
sometimes possible for the base side of the film to touch the 35mm pad
rollers. This can cause base side scratches, which show up as dark
lines about 1/4 of the picture width from each side. Those "in the
know" will remove the 35mm pad rollers when showing a 70mm print, and
replace them with spare 70mm rollers. This allows them to turn the
knob either way without creasing the print, and at the same time
eliminates the risk of base-side scratches.
As a footnote, the lamphouse generally must be readjusted for 70mm as
well, to cover the larger frame area.
5.11 What are the differences between nitrate-, acetate-, and polyester-based
print stocks?
5.11.1 Nitrate Base/Triacetate (Safety) Base
Early motion pictures were all shot and printed on nitrate-base film.
This became extremely flammable as it aged, and thus unsuitable for
use in non-fireproofed environments (such as homes and schools). Thus,
`safety film' was invented, which had a biacetate (later, triacetate),
or similar, base. This was initially used for 16mm films (which were
never manufactured on nitrate [except in Russia, for a short time],
due to concerns about home use), and eventually came into use for 35mm
presentation as well. The last nitrate film manufactured by Eastman
Kodak (tm) was delivered in 1953. With the introduction of safety
film, the projection and storage of nitrate films was outlawed or
severely restricted by many communities. As film librarians have
found, nitrate, being an unstable base by nature, tends to decompose
easily, and many old nitrate films which have not been re-printed onto
safety film have deteriorated beyond the point of recovery. When
nitrate prints are shown today, it is common to remove a small piece
of head or tail, and light it. The speed at which the film burns can
be used to determine whether or not the film can be run in relative
safety. Kodak (tm) distributes a booklet on "Safe Handling and Storage
of Nitrate Motion Picture Films."
5.11.2 Polyester Base
Polyester stock (`ESTAR (tm) ' is a trademark for polyester stock
manu- factured by the Eastman Kodak (tm) company) is a fairly new
development for print film. Like triacetate stock, it is nonflammable.
The primary differences between it and the older nitrate/triacetate
stocks are strength and thickness. Unlike other films, polyester stock
does not break. If stressed, it simply stretches. This can be either
good or bad, depending upon the degree to which it is stressed; for
example, a jammed platter feed mechanism can cause the still-running
projector to pull an essentially immovable piece of film through it,
causing great damage to the projector itself, and, of course, damaging
several feet of the film. If this circumstance occurred with
triacetate film stock, the film would have simply broken, and no
damage would have occurred.
The severity of this and other problems varies substantially among
films manufactured by different companies. Further, the resistance to
breakage is the primary reason why polyester is not used on camera
films, as the risk of damage is much greater when the film is run
through expensive camera equipment. (Polyester camera film is
manufactured and used for high-speed cameras used to capture
slow-motion images for scientific and engineering work, as the
mechanisms of these cameras run so quickly that they would be severely
damaged if the film were to break while the camera was running).
Polyester stock is also thinner and lighter than acetate stock (one
can identify it as polyester by holding a reel up to a light source in
a sideways position (such that it appears round from the viewer's
point of view); if one can see light through it, then it is
polyester). This can reduce the number of shipping reels, and the
shipping cost, but may require adjustment of gate pressure in the
projector in order for the film to run properly. Also, the stock is
more sensitive to low humidity than triacetate, as it tends to pick up
static electrical charge, sometimes preventing it from running
smoothly on a platter system. The most often recommended solution to
this ailment is to ensure that the platters are properly grounded, and
that a humidifier is present in the projection booth. This will also
help to avert unnecessary dust accumulation on the print.
The texture of polyester stock is substantially different from that of
triacetate stock, and cement splices are not useful on polyester films
(either tape or ultrasonic splices must be used). Thus, projectionists
usually use the more-visible tape splices to join film together.
The static and strength problems were particularly acute with many
prints of American President, one of the first major features to have
35mm prints distributed on polyester stock. Commonly, when run on
platters, the film layers would `stick' together, jamming the feed
mechanism, and, usually, causing the whole projector to stop (by means
of `failsafe' assemblies which stop the motor when there is excessive
tension on the guide rollers).
It should also be noted that the IMAX (tm) format requires that
polyester-based film be used, due to the relatively high linear speed
at which the film moves through the projector (about three times that
of 35mm), and the potential damage to the projector should there be a
film break in the middle of a show. However, IMAX (tm) equipment was
designed for polyester film, and has several safeguards not present in
most 35mm projection equipment in order to avert potential disasters
in the projection booth.
5.12 What is the best way to avoid the static and shedding problems common in
polyester prints?
Opinions and experiences on this topic vary widely; most, however,
agree that the following suggestions are at least somewhat helpful for
reducing the problems associated with polyester prints; these prints
can be identified by their inability to break (for example, by trying
to tear off a bit of hea |
