Figure 7-17 shows the focal length of a standard 50mm lens.
Figure 7-17.The focal length of a standard lens.
Focal length, imprinted on the lens mount at the front of the lens barrel, is
sometimes expressed in inches, sometimes in millimeters (mm), and
occasionally in both systems.
Figure 7-18 shows a lens barrel with the imprinted focal length of the lens
Figure 7-18.A lens barrel showing
the focal length designation.
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