The standard 8 mm (also known as regular 8) lm format was developed by the Eastman Kodak company during the Great Depression and released on the market in 1932 to create a home movie format that was less expensive than 16 mm. The lm spools actually contain a 16 mm lm with twice as many perforations along each edge than normal 16 mm lm; on its rst pass through the camera, the lm is only exposed along half of its width. When the rst pass is complete, the camera is opened and the spools are ipped and swapped (the design of the spool hole ensures that this happens properly) and the same lm is then exposed along its other edge, the edge left unexposed on the rst pass. After processing, the lm is split down the middle, resulting in two lengths of 8 mm lm, each with a single row of perforations along one edge, thereby yielding four times as many frames from the same amount of 16 mm lm — and hence the cost savings. Because of the two passes of the lm, the format was sometimes called Double 8. The frame size of regular 8 mm is 4.8 mm x 3.5 mm and 1 meter of lm contains 264 pictures. Normally Double 8 is lmed at 16 frames per second.