This is used to describe the area of a film used by a camera to record a photo. A 35mm format camera records a 24x36mm image on the film. Medium format cameras record anything from 6x4.5cm to 6x17cm on 120 and 220 roll film. When choosing a medium-format some photographers prefer the square 6x6cm format because it offers an alternative shape to the conventional oblong, but also saves you having to think in a portrait or landscape way. The cropping can be done later when printing the results. As the format increase potential quality improves, while the number of pictures that can be recorded on a roll of film decreases. You can shoot 15 pictures on a 6x4.5cm camera, 12 on a 6x6cm camera and 10 on a 6x7cm camera and just 4 on a 6x17cm camera.