User's Manual

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Depth-of-field scale
The plane which is rendered sharpest is the
plane, parallel to the film, upon which the lens
is focused. The optimum sharpness decreases
progressively in front of and behind this plane
such that a certain range exists within which
the image is, to the eye, rendered sharply.
This range is termed the depth of field. It is
dependent on the focus setting, the focal
length of the lens (the two values together
determine the reproduction scale) and the
aperture. Stopping down, i.e. selection of a
larger f-number, increases depth-of-field,
whilst widening the aperture, i.e. selection of a
smaller f-number, decreases it. The depth-of-
field scale in conjunction with the focusing ring
indicates the range of sharpness at the set
focus distance.
For example, using the LEICA SUMMILUX-M
f/1.4/50 mm lens focused at 5 metres, the
depth-of-field at f/4 ranges from approximately
4 to 8 metres. Stopping down to f/11 at the
same focusing distance, however, increases
the range to 3 - 20 metres.
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