I was going to stay out of this, since several good answers have been given, but there still seems to be some confusion.
"Letterbox" isn't an aspect ratio, it is a technique for displaying a picture that's wider than a TV screen on the TV screen without losing image by panning, scanning, cropping or zooming.
2.35:1 (the correct way to write an aspect ratio since it is a ratio, not a multiplication problem) is no more "true" than most other ratios. There have been many different aspect ratios used in film over the years. The common ones today are, indeed, 1.66:1 (used mostly in Europe), 1.85:1 (used mostly for comedies and "small" dramas), 2.35:1 (for "big" and "epic" dramatic or action films) and 1.37:1/1.33:1 used for television.
In fact, most 1.66:1 and 1.85:1 movies are shot with spherical lenses on standard 35mm film, and threfore expose a 1.33:1 frame. But they are designed for the projected aspect ratio. Getting the "whole picture" in these cases would not be desirable, because you'd be getting a "padded" frame that spoils the careful composition.
Panavision widescreen films (projected at 2.35:1) are actually photographed on normal 35mm film at a ratio closer to 2.20:1. The wide image is "squeezed" onto the narrow film by using a distorting (anamorphic) lens. This produces an image on the film in which everything is unnaturally tall and thin, but it allows a greater "angle of vision" to the camera. The distorted picture is restored to normal proportions when the movie projector is fitted with a compensating lens. "Anamorphic" or "enhanced widescreen" DVDs are created using an analogous process, except that the image is manipulated electronically in encoding the disc and by the widescreen TV in displaying the image. The two uses of "anamorphic" are not otherwise related. A film does not have to be shot with an anamorphic lens to the DVD to be anamorphic, nor does the fact that a film was shot that way ensure that the DVD will be anamorphic as opposed to "matted" letterbox.
Many films that are released theatrically at 2.35:1 are shot on Super35, just like B5, because the lighting and other shooting requirements are not as stringent as the are when shooting with anamorphic lenses, and because the filmmaker has greater control over the look of the inevitable TV/VHS/Airline version of the film, which will be seen at 1.33:1.
Titanic, Apollo 13, Terminator 2: Judgment Day are all examples of theatrical films shot in Super35. So, as it happens, are Goodfellas and Casino. You didn't see "the whole picture" with those two, in the sense of seeing the entire frame originally exposed, because no one ever sees "the whole picture" with Super35. You can't make a release print from a Super35 master because Super35 uses the area of the frame where the optical soundtrack will go on all release prints for a picture.
Regards,
Joe
