The
coverage of a
lens is the size of the
image it can produce, measured as the diameter of the
image circle produced by the optics. In a
camera system the coverage must be large enough to cover the sensor or film used. In a
view camera system, because the
film plane can be moved independently of the lens plane, the lens must have enough coverage to cover the film while it is offset from the center of the coverage area. Inadequate coverage can lead to
vignetting.