Nikon FM, Инструкция по эксплуатации

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FOCUSING - continued
Infrared Photography
The plane of sharpest focus for infrared light is slightly far-
ther away than its counterpart for visible light as seen through
the camera’s viewfinder. To compensate for this, first focus
the image sharply through the viewfinder. Then, turn the fo-
cusing ring counterclockwise until the point focused is aligned
with the red dot (or line) provided on the lens barrel. For
example, in the picture below, the lens has been focused for
infinity (oh) infrared shooting. Note that when lenses with a
focal length of 50mm or less are used stopped-down to f/8 or
below, compensation is not necessary due to the large depth
of field available.
There are some Nikkor lenses that do not require refocusing
for infrared photography; refer to their instruction manuals
for details.
Film-Plane Indicator
To ensure the best results in critical picture-taking
situations, such as close-up or copy photography, it is neces-
sary to determine the exact subject-to-film-plane distance. The
Nikon FM is thus provided with a film plane indicator ( - );
this is positioned exactly in the film plane, which is 46.5mm
from the front surface of the lens mounting flange.