PhotoNature CalculatorObject size - focal length - distance

cm m in ft m ft yd focal length mm     + scope x a b = mm ↑ 14.8 14.9 15 15.6 15.7 22.2 22.3 22.4 23 23.5 23.6 23.9 24 35.9 36 41.5 54 56 a/b =
          ( 75 %)

This calculator computes one of the following:

• animal (for example bird) or other photographed object size
• focal length of the telelens or other lens
• distance from the camera to the photographed object (or rather object distance)
• ratio of the photographed object image size to the camera sensor or film frame size

from the remaining parameters and:

• camera sensor or film frame size
• spotting scope magnification (1 if not used).

It is not applicable for fisheye lenses.