Film-Advance Lever; Frame Counter - Nikon FM Instruction Manual

Film-Advance Lever

The film-advance lever simultaneously advances the film,
cocks the shutter and operates the frame counter. It also
doubles as the Nikon FM's meter on/off switch and shutter
button lock.
To advance the film, stroke the lever with your right thumb
as far as it will go. The film will be advanced a full frame.
The lever automatically returns to its 30° stand-off position
when released upon the completion of the film advance.
The film-advance lever switches the meter on when moved
to its stand-off position; it switches the meter off when moved
back flush with the camera body. With the lever set flush
against the camera body, it serves also as a lock to prevent
accidental tripping when the shutter is cocked.

Frame Counter

Each time the film is advanced one frame by a full stroke of
the film advance lever, the frame counter operates to show
how many frames have been exposed. It is automatically re-
set to S (start), two frames before 0, when the camera back is
opened to remove an exposed film cartridge and/or load a new
roll of film. The frame counter dial has indications for up to a
maximum of 36 frames, with all odd numbers calibrated in
dots and all even numbers in figures. The figures are in white,
except for 12, 20 and 36 which appear in red to indicate the
maximum number of exposures available, respectively, with
standard film cartridges.
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