Frame Size

From Streaming 411

Frame Size and Aspect Ratios

When the first film projector, called the Kinetoscope, was unveiled by William L.K. Dickson and Thomas Edison in 1895, it used a 19mm wide film with perfs (the little holes that are used to move the film) on one side. Using only one track of perfs caused the film to become very jittery, so the inventors decided to use George Eastman’s 70 mm film, by first cutting it in half and putting perfs on both sides, thus giving birth to the 35mm film format used in the silent movie era. The effective imaging area (without the perfs) of the new medium was 24 mm wide and Dickson decided to use 4 perfs (18 mm) as the vertical dimension of the frame. This is where the 4:3 aspect ratio comes from - 24:18 = 4:3. Video aspect ratios are expressed as fractions, whereas film uses a decimal notation. For example, when a sound track was added to the 35 mm format, it shrunk the width of the frame, giving a 1,37 ratio that’s also known as the Academy format. In digital photography, 35mm is known as the “full frame” format when historically, it used to be the “compact format”.

With the popularization of television in the fifties (due to a booming economic climate and the first color tv), the motion picture industry started to come up with new ways to lure the viewers back in the cinemas. One way of achieving this was by making the image larger which meant using a new film format (CinemaScope, VistVision, Cinerama, Technirama). This resulted in a wide range of aspect ratios in the film industry: 1.37; 1,67; 1,85; 2,20; 2,35. None of these are really compatible with the more vertical 4:3 ratio, so when the standard for the next-generation (high-def) television standard were developed