26
STOP-DOWN EXPOSURE MEASUREMENT
The vast selection of lenses available for use with your Nikon
FM includes some which are fitted neither with an automatic
diaphragm nor a meter coupling ridge, both of which are es-
sential to full-aperture exposure measurement. The FM works
even with such lenses, through an alternative method called
“stop-down” exposure measurement. Note that when this type
of lens is used with the camera, the meter coupling lever
should be raised and locked up out of way manually by de-
pressing and holding the coupling lever release button; to
avoid accidental damage, make sure you do not use exces-
sive force when raising up the lever.
This is how stop-down exposure measurement is performed.
After you’ve composed your picture, move the film advance
lever to its stand-off position and press the camera’s depth-
of-field preview lever. Keep the lever pressed, and adjust
either the shutter speed dial or the lens aperture ring (or
both)—until the correct exposure indicator (a) LED lights
up. Then, release the lever and shoot.
It is advisable, at all times, to refer to the instruction manual
of the lens in use—especially if it is a fixedaperture lens (e.g.,
Reflex-Nikkor) or one requiring a focusing unit (e.g., Nikkor
1200mm f/11)—when performing stop-down exposure mea-
surement. The same applies when bellows units, extension
rings, preset lens (e.g., PC-Nikkor), etc. are used with the
FM.