Nikon F25B manual STOP-DOWN Exposure Measurement

Models: F25B

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STOP-DOWN EXPOSURE MEASUREMENT

With some Nikkor lenses, full-aperture exposure mea- surement is not possible, either because the lens has no automatic diaphragm, or because the lens does not cou- ple with the finder's meter; with certain accessories, too, lens/finder coupling is not possible, thus, preventing full- aperture measurement. However, the camera's Photomic meter can still be used for exposure measurement via the stop-down method. Before mounting the lens (or accessory) on the camera body, push the meter coupling pin up into the finder with a coin or similar object; when set, the number "5.6" will appear in the finder's maxi- mum aperture indicator. After setting the finder, mount the lens or lens/accessory combination on the camera, switch on the meter by moving the film-advance lever to the standoff position, and then set the controls for cor- rect exposure as follows:

For fixed-aperture lenses, such as Reflex-N ikkor lenses, simply adjust the shutter-speed selector until the center LED indicator comes on. For convenience, shutter speeds can be set at intermediate settings in the 1/80 sec. to 1/2000 sec. speed range for precise exposures. If the meter indicates con tinuous overexposure, use a neutral density filter or slower film. If continuous under- exposure is indicated, suppleme"ntary lighting or a faster film is necessary. This technique is also suitable for photography using a telescope or microscope"

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Nikon F25B manual STOP-DOWN Exposure Measurement