apprx. 2.60:1 aspect ratio
This method of filming actually used three cameras, after which the three images were interlocked together. Any transfer to video would be from a 35mm anamorphic reduction print and therefore have a 2.35:1 ratio. Several movies were filmed in Cinerama, including "How the West Was Won", "The Wonderful World of The Brothers Grimm", and "Seven Wonders of the World".

Cinerama also required the screen onto which the image was projected to be deeply curved or else the resulting picture would suffer gross distortion. Therefore, it is not really possible to make a "widescreen" version of a Cinerama film suitable for viewing on a television unless some form of corrections to eliminate the distortion are applied.

2.66:1 aspect ratio
2.55:1 aspect ratio
2.35:1 aspect ratio
This was once the most commonly used method of filming movies because its only major requirement was a special CinemaScope projector lens. This lens was and still is available at virtually every movie theatre. CinemaScope was originally created by 20th Century Fox, but it is no longer in use in its original format.

The 2.55:1 ratio was pretty much dead by 1957 when the last holdout, Fox, adopted magoptical over mag only prints. From that point until the early 1970s a standard of 2.35:1 was used; however, there is usually slight matting in theatres which results in a theatrical aspect ratio closer to 2.40:1. All of the "Star Wars" movies and even the 1997 animated version of "Anastasia" were filmed in CinemaScope, as were classics like "The Robe" and "20,000 Leagues Under the Sea."

Super Panavision 70
2.20:1 aspect ratio
Super Panavision 70 was a 70mm version of the Panavision process meant to compete directly with the 70mm Todd-AO process. Super Panavision 70 has also been known as Panavision 70, Super Panavision, Panavision, and Panavision Super 70. With an anamorphic lens, SP70 movies could have a final aspect ratio of 2.76:1. Famous movies that were filmed in Super Panavision 70 are "My Fair Lady", "2001: A Space Odyssey", and "Chitty Chitty Bang Bang".

Ultra Panavision 70
2.76:1 aspect ratio
(65/70mm prints)

2:35:1 aspect ratio
(35mm prints)
Ultra Panavision 70, created by MGM, was created to compensate a shortcoming with the original CinemaScope format called "CinemaScope mumps" where close-up images in the center of the screen did not get compressed properly. UP70 used anamorphic lenses and a consistent frame rate of 24 frames per second, which was not yet a standard among the various film formats. This was done with a camera that MGM called the "MGM Camera 65".

UP70 was used to film some of the most popular movies in movie history, like "Ben Hur", "Mutiny on the Bounty", and "It's a Mad, Mad, Mad, Mad World".

2.40:1 aspect ratio

various aspect ratios
The Panavision company is now the most successful maker and distributor of lenses and filming equipment. In the 1970s their Panavision lenses became the "standard" for widescreen and non-widescreen movies. Panavision still makes or sells the lenses for most of the major studio productions today, including lenses for films made with matting as opposed to true widescreen. These matted films are not necessarily 2.40:1, but are most likely 1.85:1.

Because Panavision now represents the manufacturer and distributor more than the filming process, it is not uncommon to see that many television shows are filmed with Panavision lenses. Therefore, it is important to note that "Filmed with Panavision cameras and lenses" does not automatically constitute a widescreen process.

1.66:1 aspect ratio
1.85:1 aspect ratio
2.0:1 aspect ratio
This system was a lot looser than others, allowing for a bit more fudging. But Paramount's specs always referenced a preferred A/R of 1.85:1. All VV prints were hard matted to around 1.66:1 to allow some flexibility in framing.

VistaVision movies were filmed with a specially designed camera which was mounted on its side. This special filming method required a special projector, but its image quality was better than standard 35mm.

Movies that are shot in VistaVision were photographed on a double width frame of 35mm running right to left horizontally. The films were generally "reduction printed" to 35mm 4-perforated (four sprocket holes per frame) in dye-transfer Techniclor and projected with a 1.85:1 ratio. The image area was extracted optically from the full frame. For some special venues the double-frame 35mm film was cropped to 1.85:1 during projection. VistaVision movies include "Vertigo", "North By Northwest", and "White Christmas".

2.2:1 aspect ratio
(during filming)

2.35:1 aspect ratio
(final 35mm print)

This process uses a 65mm negative printed onto 70mm film, with a six-track soundtrack, producing a very high quality picture. The original filming was done in an aspect ratio of 2.2:1; however, during the printing to 70mm film, the aspect ratio ended up being closer to a 2.35:1 aspect ratio. The original Todd-AO format also was shot at 30 frames per second, as opposed to the current standard of 24 frames per second.

Many of the great epics and musicals of the 50s and 60s used this format.

2.2:1 aspect ratio
(70mm prints)

2.35:1 aspect ratio
(35mm prints)
This process was developed by the Technicolor Corporation, as a way to continue using its three-strip Technicolor cameras. It required both a specially developed camera to run the film sideways (like VistaVision) with a widescreen lens (like CinemaScope).

Technirama was shot with VistaVision cameras and an anamorphic lens squeezing the image by 25%. The entire 1.5:1 image area was then either optically unsqueezed to 70mm yielding a 2.21:1 aspect ratio, or given an additional squeeze to 35mm 2.35:1 4-perforated (four sprocket holes per frame) Panavision. For purposes of video transfer only an A/R of 2.35:1 would apply since there was never a 65/70mm negative involved in the process.

1.33:1 aspect ratio

1.37:1 aspect ratio
The Academy ratio (1.37:1 before a soundtrack was incorporated onto the film) was the primary original aspect ratio. Most movies (if not all) that were released before "The Robe" (the first movie to be shown in widescreen) were shown in this ratio.

When televisions first came on the scene, they were (and still are) designed with an aspect ratio matching the Academy ratio so that movies would be shown in the same way as in the theatres. Movies that were filmed in an Academy ratio will not have a "widescreen" version because they fit perfectly on the TV. Such movies include "The Wizard of Oz", "Casablanca", "Citizen Kane", and many, many others.

Super 35
This process does not involve widescreen lenses, but rather it involves framing the picture to fit the ratio of the screen. The top and bottom of the frame are "matted" out and removed from the picture completely, resulting in a rectangular picture.

Super35 movies are filmed using flat lenses. Using an optical printer, the "interpositive" image is then contact-printed to produce an "internegative" anamorphic release print. As a result, an anamorphic image from a Super35 original tends to have a "gritty but sharp" look that is "harder" in a way than an anamorphic image, which has a "smooth" look.

Many movies made in Super35 are transferred to video with the top and bottom of the frame restored, so that you actually see more of the picture on video than you did in the theater. However, scenes which include special effects in them are almost always filmed hard-matted in the appropriate widescreen ratio and therefore must be subjected to the pan-and-scan process.

The image above is from James Cameron's Terminator 2. The red area represents what you see in the theatrical version. The blue represents the "pan-and-scan" version, although as you can see there is no panning or scanning.

Open Matte
variable aspect ratio
(usually 1.66:1 or 1.85:1)
Open matte is similar to Super 35 in that it involves matting out the top and bottom of the frame for the theatrical release and removing the mattes for the home video release.

Most open matte films are filmed directly on the entire 1.33:1 frame. This can dramatically increase the potential for unexpected material such as boom mikes to appear in the home video version. In fact, some directors simply placed cardboard on the monitors to simulate the matted theatrical version. This would have made them unaware during filming if the boom mikes and so forth were actually on the frame because the cardboard was blocking that part out.

Table courtesy of www.widescreen.org