ZOOMING C
To zoom in or out, simply turn the zoom ring until the desired composition is
tramed on the focusing screen. The ring has a four-position scale showing which
of five focat lengths—25mm, 28mm, 35mm, 40mm and 50mm—is in use in case
you want to preset the lens to any of these focal lengths.
Caution:
Slight vignetting will occur when you shoot with the lens at a small
aperture, at its closest focusing distance and at a wide angle focal length.
DEPTH-OF-FIELD SCALE
Unlike other Nikkor lenses, the Zoom-Nikkor 25-50mm f/4 has no color-coded
depth-of-field indicators engraved on the lens barrel. However, you can still
determine the depth of field by using the scales provided with this pamphlet.
To use, first cut out the scales along the lines indicated. Then, place the sub-
ject-distance scale (B) over the depth-of-field scale (A) with the top edge of ihe
(B) scale lined up with the focal length in use and the focused distance aligned
with the (A) scale's central indicator line. Now read off the numbers (on the B
scale) which appear opposite the pair of depth-of-field lines (on the A scale)
corresponding to the aperture in use; these numbers express the depth of
field lor the settings in use.
For example, if the lens is prefocused at 1.5m (5 ft) with the focal length set at
35mm and the aperture at f/16, the numbers on the distance scale opposite
the depth-of-field lines for the f/16 setting show that the depth of field extends
from 1m
(3.511)
to 3m (10 It). You can also observe the depth
o1
lield through the
viewfinder by pressing the depth-of-field preview button on the camera.
INFRARED PHOTOGRAPHY D
The plane of sharpest focus for infrared light is slightly more distant than
its counterpart for visible light as seen through the camera viewfinder. Thus,
for the sharpest focus in infrared photography, adjustments must be made.
The scales provided can be used for determining the amount of adjustment via
the dotted infrared compensation line included.
In the same manner as described in the "depth-of-field scale" section, match
the prefocused subject distance (using the B scale) with the focal length and
aperture scale central indicator line (on the A scale). The distance from the
central indicator line to the dotted compensation line represents the amount of
adjustment required. Now, turn the lens' focusing ring counterclockwise
until the prefocused distance is shifted as prescribed on the scales.
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