Focal Length Limitations - Nikon D300 Complete Manual

Finally, note that if you use the MB-D10, you may need to use
a short extension tube to use bellows or other accessories that
stick far down below where lenses normally do.

Focal Length Limitations

Because Nikon chose to retain its F mount on the D300,
virtually every lens Nikon has made in the past 30 years can
be mounted on a D300. But the field of view you see in the
viewfinder is different on a D300 than on a 35mm film body.
The D300 crops the field of view by about 1.5x. This means
that a 14mm lens mounted on a D300 has about the
equivalent field of view of a 21mm lens mounted on a 35mm
film Nikon body (see the table later in this section).
Field of view changes when a Nikon lens is mounted on a
D300 because the camera's sensor is physically smaller than
the 35mm frame for which it was originally intended. Note
that I keep using the term "field of view." The focal length of a
lens is absolutely unchanged when you mount a lens on a
D300. Indeed, the resulting image on a D300 is no different
than if you took a picture with a 35mm body and then
cropped it down to the smaller sensor area of the D300
Note: I've read reports from professionals and editors who should
know better that go something like this: "The D300's 1.5x
magnification is like getting a 1.4x extender for free, with no
aperture penalty." Sorry, but that's not really true. If you
mount a 400mm f/2.8 lens on your 35mm body and then
crop the resulting image to a ~28mm diagonal section in the
middle, you'd get exactly the same image as you get from
the D300.
105
In an earlier edition of this eBook, someone challenged that assertion in regards to
depth of field. But if you use the Zeiss method of depth of field calculations, as most
people do, you'd have to change your Circle of Confusion value for the cropped
35mm image to match that of the APS-sized digital sensor. Thus, printed at the same
size, they would look the same.
Thom Hogan's Complete Guide to the Nikon D300
V1.02
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