Mamiya 7 II - Manual (Page 36)

Photographing to conform to purposes
Diopter Correction Lenses
Six types of diopter correcting lenses are available for
near/farsighted people. Mount as indicated above.
Powers available are: +3, +2, +1, -1, -2, and -3.
+: Far-Sighted
-: Near-Sighted
Depth-of-Field
The depth-of-field varies according to the aperture. The
smaller the aperture (f/8, f/11, f/16...) the greater the
depth-of-field; the larger the aperture (f/8, f/5.6,...) the
smaller the depth-of-field. To take pictures which are
sharp from foreground to infinity or when taking
snapshots, the focusing range is extended or depth
increased by using a smaller aperture. When the subject
is to stand out, with the background out of focus, a larger
aperture is appropriate.
The depth-of-field scale on the lens indicates
depth-of-field in terms of the distance between subjects
on both sides of the scale. For example, when a 80mm
lens is stopped down to f/22, respectively, all objects
located within the ranges shown in the illustrations above
will be sharp.
* Refer to the instructions attached to individual
lenses for specific depth-of-field tables.
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