Nikon F4 - Manual (Page 93)

For lenses with fixed apertures
Because the aperture of a Reflex-Nikkor lens is fixed, in photo­
micrography or telescopic photography, it is impossible to
change the exposure by varying the aperture.
In A mode:
The F4’s computer will automatically adjust the shutter
speed. Take the picture by simply depressing the shutter
release button.
In M mode:
Select the appropriate shutter speed (in 1 EV steps) for
correct exposure. If a correct exposure cannot be obtained,
use either an ND filter (if the scene is too bright) or supple­
mentary illumination (if too dark).
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