There is a lot of confusion regarding the different screen formats available on today's DVDs.  What I hope that this guide will do is explain the origins, timelines and evolution of different aspect ratios.  It is by no means exhaustive, nor should be taken as an absolute authority.  I have culled this information from my experience in the film industry, along with information that is readily available on the internet.

1.33:1, Academy Standard, NTSC Television (4x3)

First, since film predates television by roughly 50 years, we shall start there.  Originally, the aspect ratio used was 1.33:1 in the film industry.  This works out to the ratio being  4 x 3, or 4 units wide for every 3 units high.  Actually, the true ratio was 1.37:1 but for the sake of this guide, we will keep to the norm of 1.33:1.  Films were shot in this ratio, and projected in theatres in the same ratio.  This was the norm from the 1890's through the early 1950's.  1.33:1 is also know as the Academy Standard, so named for The Academy of Motion Picture Arts and Sciences, which recognized it in the 1930's.

In the early 1950's, television made it's debut and the 1.33:1 ratio was chosen as the standard by the National Television Standards Committee (NTSC).

Widescreen

As the film industry started to push forward with new technologies, new ratios started to emerge.  In 1953, 20th Century Fox introduced Cinemascope, used from 1953 to 1967.  This eventually gave way to to Panavision.  There were many different ratios used under these names, but two standards emerged:

• 1.85:1  Academy Flat
• 2.35:1  Anamorphic Scope (Cinemascope / Panavision)

Two lesser formats were also used, which are:

• 1.66:1
• 2.20:1 (70mm)

Film Conversion / Transfer

I will not go into too much detail regarding the actual transfer from one media to another, suffice it to say that the film houses have always been experimenting with different methods to transfer the image from one ratio to another. There are two predominant methods which are pan and scan, and letterbox format.

Pan and scan is commonly know as "full frame," but what this really means is that the original image has been modified to fit the TV aspect ratio.  Pan and scan involves having the camera move back and forth across the film image to keep the important parts centered on the TV screen.  Other methods of video compression result in a distorted image.  The problem with pan and scan, along with other methods of transfer, is that up to 50% of the original image is lost. As well, the widescreen oriented composition is lost.  The tell-tale is at the beginning of the film, the rider states that 'this film has been modified from its original format. It has been formatted to fit your screen.' 

Letterbox format involves the the entire film image being transferred to the TV screen, keeping the aspect ratio along the width, and necessitating the black bars on the top and bottom of the screen to block the unused portion of the screen.  Some people find these bars distracting, or the image presented on the screen is too small.

16 x 9 (Widescreen TV) 1.78:1

With the advent of the digital age, newer technologies have emerged and a new standard of television aspect ratio has become the standard.  This ratio is 1.78:1, commonly referred to as 16 x 9, or widescreen TV. This is the Digital TV standard, or DTV.  New films being transferred indicate that they are 'enhanced for widescreen TVs' to take full advantage of the 16 x 9 ratio and digital technology present in the encoding of the DVDs to best reflect the original widescreen format of the film.

With this technology, we can watch the movie in it's original aspect ratio, the way it was filmed, the way it was intended to be viewed; and experience everything that the director wanted to convey in the film.  Isn't that what watching movies is all about?

So there you have it. I hope that this primer helped in clearing up some of the mystery behind aspect ratios, film formats and how the technology has evolved. For more detailed information, search the net under Aspect Ratios.

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Thanks, 

The Snowstorm.