Nikon Micro-Nikkor 200mm f/4 IF Manuel d'instruction - Page 9

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Depth of Field

Depth of field refers to the zone of acceptable

focus extending in front of and behind the

plane of sharpest focus. As this zone is excep-

tionally shallow at high reproduction ratios,

previewing is desirable before shooting. To pre-

view, press the depth-of-field button on the

camera and the lens will close to the preselect-

ed aperture to allow you to see how much

background and foreground is in focus. Depth

of field can also be observed by reading the

color-coded indicators inscribed on the lens

barrel. A pair of orange lines on either side

of the white distance scale index line corre-

sponds to f/32 which is the same color on the

aperture scale. At close distance, so little is in

focus that the depth-of-field tables on pages

13 ~ 14 are more useful.

NOTES ON FOCUSING

To avoid camera shake, close-up photog-

raphy poses several problems not encoun-

tered in general photography. One of these

is sensitivity to vibration: the magnifica-

tion of the image on the film makes even

slight image displacement prominent and

results in a blurred image. Therefore, for

best results, mount the camera on a tripod

or on rigid supports, and use a cable release

to trip the shutter.

At extremely close working distances, depth

of field decreases to the actual focused

distance. This can be partially compensated

for by stopping down the lens. But at very

close distances an extremely narrow depth

of field is inevitable. Careful placement of

the subject, if it has depth, will be neces-

sary to ensure that the important surfaces

will be in the same zone of sharpness.