SECTION IV
PRACTICAL CAMERA LENS DATA
2-21. GENERAL.
Photographers often require conversion tables and simple
formulas to work out camera lens settings and reproduction ratios.
This
section contains information to solve some of these common problems in
photography.
2-22. CAMERA LENS SIZE CONVERSION TABLE.
When working with photographic
lenses, the photographer will often be faced with the problem of converting
relatively small measurements from inches into millimeters, or from millimeters
into inches. Table 2-4 greatly simplifies conversion of such measurements.
Table 2-4.
Camera lens size conversion table.
2-23. FOCAL LENGTH. Focal length is the distance from the optical center of a
lens to the film plane when the lens is focused at infinity. Focal length is
calculated by the manufacturer when the lens is made.
It is stamped on the
lens barrel.
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