Infrared picture-taking
In infrared photography, the plane of sharpest image is slightly more distant
than the one produced by visible light and seen by the naked eye through the viewfinder.
To compensate for the shTh in focus, Nikkor lenses have a red dot or line engraved
on the lens barrel near the color-coded depth-of-field index scale on top of the
lens. After focusing the image sharply through the viewfinder, turn the focusing
ring to the left until the red dot lines up with the prefocused distance.
For example,
in the picture below the 50mm f/1.4 lens has been focused at infinity (oo). The focusing
ring is turned slightly to the left so that the infinity marking appears in line
with the red dot When a lens having a focal length of 50mm or less (normal or wideangle)
is used at an aperture of f/8 or smaller, no adjustment is necessary. The lens has
sufficient depth offield at such small i apertures to compensate for the shift in
focus.
Intentional double exposures can be made with the Nikon F as follows: After making
the first exposure, set the A-R ring around the shutter release button to "R"
and turn the rewind crank in the direction of the arrow until the red dot on the
shutter release button rotates a full 360 degrees (or slightly more). Reset the A-R
ring to "A" and wind the shyster for the second exposure. The film winding
is confirmed by checking the red dot on the shutter release button which rotates
a full 360 degrees. Any shutter speed may be used for the second exposure.
The exposure counter will not compensate for the rewinding, so the film in the camera
will actually have one frame or two more than indicated.
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