Nikon Nikon Nikomat FT, Nikon FA manual Depth of Field

TECHNICAL INFORMATION/PHOTOGRAPHY TECHNIQUES continued

DEPTH OF FIELD

When you shoot at a certain aperture and focusing distance, you will find that not only the main subject but also objects within a certain range in front of and behind it will be sharp in the final photograph This in focus zone'' is known as depth of field Objects beyond this range become increasingly out of focus. When the zone of sharpness is large, depth of field is deep: when it is small. depth of field is shallow.The following is true of depth of field:

1)The smaller the shooting aperture (i.e., the larger the numerical f-number), the deeper the depth of field; the larger the aperture, the she lower the depth of field.

2)The farther away the subject is from the lens, the deeper the depth of field becomes; the closer to the lens, the shallower the depth of field.

3)The longer the focal length of a lens, the shallower the depth of field at each f/stop, the shorter the focal length, the deeper the depth of field.

4)There is greater depth of field behind the main subject than in front of it.

The depth of field at each aperture is indicated on the lens by a set of color-coded lines 62 (corresponding to the colors of the f- numbers on the aperture ring 65 ) which are used in conjunction with the distance scale 63 on the focusing ring 45 ). The range is indicated by the distance between the lines.

When a lens with an automatic diaphragm is used, the image in the viewfinder is viewed with the lens at maximum aperture. However, when the depth-of-field preview lever's is pushed down, the lens will be stopped down to the aperture set, enabling you to examine depth of field before shooting The image in the viewfinder darkens according to the selected f-number, the smaller the aperture, the darker the image. Portions of the picture that appear in focus when the lever is pushed down-will be in the zone of sharp focus.

Note that the lever should be depressed all the way.

This lever is also used for stop-down exposure measurement (refer to page 54.)

•Certain Zoom-, Reflex-, and PC-Nikkor lenses do not have a depth-of-field scale

•Pushing the lever automatically changes the metering method from automatic multi-pattern to centerweighted

•Depth-of-field can be previewed only in the A and M modes

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