Nikon D90 User Manual page 248

Compatible Lenses
CPU lenses (particularly types G and D) are recommended for use with the D90. CPU
lenses can be identified by the presence of CPU contacts, type G and D lenses by a
letter on the lens barrel. Type G lenses are not equipped with a lens aperture ring.
CPU contacts Aperture ring
CPU lens
TypeG lens Type
o
lens
Pal
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 D90, in contrast, is 23.6
x
15.8 mm, meaning that the picture angle of a 35mm camera is
approximately 1.5 times that of the D90. The approximate focal length of lenses for the D90 in
35 mm format can be calculated by multiplying the focal length of the lens by about 1.5.
Picture size (35mm format)
Lens
(36 x24mm)
Picture diagonal
Picture size (090)
(23.6 x 75.8 mm)
Picture angle (35mm format)
Picture angle (090)
Pal
Lens f-number
The f-number given in lens names is the maximum aperture ofthe lens.
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