· DEPTH OF PHOTOGRAPHIC LENSES AND THEIR UTILIZATION
Photographic lenses are capable off providing sharp focus in front of and behind the subject
actually focused on. For instance, you are shooting at F2, if you focus on a subject 10 feet away
from your lens objects closer than 7-5/8 inches and further than 8-3/4 inches from your main
subject will be in acceptable sharp focus. The front limit to the rear limit in acceptable sharp focus
is called the " Depth of Field " of a lens. This " Depth of. Field" range is shallow in the foreground
and deep in the background and the limits vary with different lens openings and distances. In actual
use the control of the " Depth of Field " serves as a tool to achieve desired effects and is utilized in
the following two ways.
F2 F5.6
1. To obtain sharp image of subject located at different distances.
2. To limit sharpness and concentrate attention on a specific part of the scene by having only the
specific " scene " sharp.
Opposite to the distance scale on the lens
barrel is a depth of field scale with lens
openings 16, 11, 8, 4, 2 engraved. These, in
conjunction with the distance scale give you
the range of the depth for a selected lens
aperture. The following method describes
this feature. For instance, when taking a
picture with your subject at 5 feet (1.5 meter)
with lens opening at f/16, the range between
the two 16s found on the scale is the distance
of acceptable sharp focus. As you can see
from the distance scale the front limit is 4feet
(1.2 meter) and the rear limit 7 feet (2
meters).
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