User Guide

The Depth

The DepthThe Depth

The Depth-

-of

ofof

of-

-Field Scale

Field ScaleField Scale

Field Scale

The picture reproduces sharpest those parts of the scene which are at the exact distance –

in a plane parallel to the film – on which the lens is focused. This maximum sharpness

gradually falls off in front of, and behind, that focused distance, resulting in a certain zone

within which everything is still acceptably sharp, The extent of this zone of sharpness – the

"depth of field" – depends on the subject distance, the focal length of the lens, and the

aperture. Stopping down increases the sharp field, which is desirable for most subjects

extending appreciably in depth. This also explains the importance of aperture control in

photography.

To find the limits of this zone, look at the depth of field scale of your lens. The sharp zone

is that enclosed between two index lines of the same aperture number. If, for instance, you

have set your 50mm SUMMICRON lens to 15 feet, the available depth of field with an

aperture of f/4 (see red arrows in the

illustration) extends from about 12

to 20 feet. If, however, you stop down

to f/11, the zone of sharpness covers

a field from about 9 to 40 feet. (When

altering the aperture, be sure to adjust

the exposure time accordingly.)