Nikon N90 instruction manual

TO CONFIRM SHARPNESS BEFORE SHOOTING-DEPTH-OF-FIELD PREVIEW BUTTON

Note that when you'reusing a lens with an automatic	While the depth-of-field preview button is depressed, shutter
diaphragm, which is what most Nikkor lenses have, the	speed indication disappears and F- - appears in the LCD
viewfinder image you see is one with the lens fully open (i.e.,	aperture readouts; also, the shutter is locked.
lens at maximum aperture). This enables you to view the depth
of field before you take the picture, with the N90'sAperture-
Priority auto or Manual exposure mode.
Depress the depth-of-field preview button to stop the lens
down to the aperture set. The image viewed becomes
progressively darker as the aperture gets smaller. Portions of
the picture that appear in focus when the button is pushed
down are within the depth of field.

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