Nikon 25215 manual Picture Angle and Focal Length, 242, Calculating Picture Angle

Technical Notes—Optional Accessories

CPU lenses can be identified by the presence of CPU contacts. Type G lenses are marked with a “G” on the lens barrel, type D lenses with a “D.”

CPU lens Type G lens Type D lens

Type G lenses are not equipped with a lens aperture ring. Unlike other CPU lenses, there is no need to lock the aperture ring at the minimum aperture setting (maximum f/-number) when using a type G lens.

Picture Angle and Focal Length

The diagonal picture angle of the D2X is less than that of a 35-mm cam- era. When calculating the focal length of the lenses for the D2X in 35-mm format, multiply the focal length of the lens by about 1.5 (high-speed crop mode off) or 2 (high-speed crop mode on):

	Approximate focal length (mm) in 35-mm format
Picture angle			(modified for picture angle)
35-mm film camera	17	20	24	28	35	50	60	85
Hi-speed crop: Off	25.5	30	36	42	52.5	75	90	127.5
D2X Hi-speed crop: On	34	40	48	56	70	100	120	170

35-mm film camera	105	135	180	200	300
Hi-speed crop: Off	157.5	202.5	270	300	450
D2X Hi-speed crop: On	210	170	360	400	600

Calculating Picture Angle

The size of the area exposed by a 35-mm cam- era is 36 × 24 mm. The size of the area exposed

Lens

by the D2X, in contrast, is 23.7 × 15.7 mm (high-speed crop off) or 17.7 × 11.7 mm (high- speed crop on). As a result, the picture angle of photographs taken with the D2X differs from the picture angle for 35-mm cameras, even when the focal length of the lens and the distance to the subject are the same.

400 500 600

600 750 900

800 1000 1200

Picture size (35-mm format) (36 mm ⋅ 24 mm)

Picture diagonal

Picture size

(D2X; high-speed crop off) (23.7 mm ⋅ 15.7 mm)

Picture size

(D2X; high-speed crop on) (17.7 mm ⋅ 11.1 mm)

Picture angle (35-mm format)

Picture angle

(D2X; high-speed crop off)

Picture angle

(D2X; high-speed crop on)

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