Nikon D300 User Manual page 382

B
Calculating Picture Angle
The size of the area exposed by a 35-mm camera is 36
x
24 mm. The size
of the area exposed by the 0300, in contrast, is approximately
23.6
x
15.8 mm, meaning that the diagonal picture angle of a 35-mm
camera is approximately 1.5 times that of the 0300. To calculate the focal
length of lenses for the 0300 in 35-mm format, multiply the focal length
of the lens by 1.5 (for example, the effective focal length of a 24-mm lens
in 35-mm format would be 36 mm when mounted on the 0300).
Picture size (35-mm format)
356
Lens
(36 mm
x
24 mm)
Picture diagonal
Picture size (0300)
23.6 mm x 15.8 mm)
Picture angle (35-mm format)
Picture angle (0300)