Aspect Ratio is a fundamentally simple concept with a deep and important history.
Simply put, the aspect ratio is the ratio of the width of the image to the height. This can be expressed as two numbers like 4x3 or 16x9 or as a decimal such as 1.85 and 2.35 - though these can be written as a ratio as in 2.35:1.
But how did it all begin? Let’s turn the dial of history and look back at the very first aspect ratio of the very first motion pictures.
The First Films
We owe the first aspect ratio to one man: William Kennedy Laurie Dickson. Dickson worked at Thomas Edison’s Lab as a staff photographer. After Eastman Kodak began mass producing flexible film in the early 1890s, Thomas Edison wanted to put this new film to use in a device called a Kinetescope - the precursor to the projected film. After a few years of start and stop experimentation, they finally arrived at a working prototype.
Using 35mm film Dickson settled on an image that was 4 perforations high - resulting in an image that was .98” by .735” - a 4:3 aspect ratio - or 1.33
We really don’t know why William Dickson settled on 4 by 3 but it stuck. In 1909 the Motion Picture Patent Company (a trust of major American film companies who were all practically under the thumb of Thomas Edison himself) declared that 35mm film with Edison perforations, and 4x3 aspect ratio with an image 4 perforations high as the standard for all films that were to made and shown in the US. This settled it - making film and projection ubiquitous across the United States.
And for a whole generation, everything stayed pretty much the same. When synchronized sound came in the scene in 1929 and optically printed on the film itself as a strip that ran along side of the image, there was a slight shift in the aspect ratio.
In 1932, the Academy of Motion Picture Arts and Sciences voted on and declared that in order to make room for the sound track, the image should be masked off on the top and bottom for a 1.37 aspect ratio (so close to 1.33 that it’s sometimes used interchangeably). This image size would be called the Academy Ratio and it remained the standard in Hollywood for yet another generation of movie goers.