ABSTRACT
A camera is essentially a light-tight box with a lens at one end to form an optical image and a fixture to hold light-sensitive material at the other to record this image. Most cameras have some means of focusing the image sharply at the photoplane for subjects at different distances. The 120 roll film size, using film of 62 mm width or 'gauge' and a backing paper, provides medium formats such as 60 x 60 mm. Adaptors can provide alternative smaller formats, for example roll-film backs for technical cameras and 35 mm film adaptors for 120 size roll-film cameras. Many types of camera have been produced both for general applications and for specialized purposes in conjunction with a range of accessories. Smaller apertures are selected by 'weather' symbols on an aperture control. The lens is fixed-focus, set at the hyperfocal distance to give reasonably sharp focus from 2 m to infinity.
