Nikon D300 Complete Manual page 373

V1.02
magazines or on the Internet, some criticisms of lenses may
106
not apply when that lens is used on a D300 .
For example, most wide angle lenses have light falloff in the
corners when used wide open (at their widest aperture).
Because the D300's sensor never sees those corners, light
falloff may not be an issue for such lenses mounted on a
D300. A good case in point is the Nikkor 18-35mm f/3.5-
4.5D ED lens. On a 35mm body with the lens zoomed to
18mm and the aperture set to f/3.5, very visible falloff can be
seen in the corners of the image, perhaps as much as a half
stop at the extremes. When that same lens is mounted on a
D300, most of the falloff disappears because the D300
doesn't see that image area! Still, there's perhaps a fifth of a
stop falloff at the settings just cited—lower than you'd see on
a 35mm body, but still present.
The 18-70mm f/3.5-4.5G DX lens included with the D70 "kit"
uses a smaller image circle than earlier 35mm lenses (it barely
covers the smaller digital sensor size used by the D300), so at
18mm and the aperture set to f/3.5, it does show visible falloff
when you use it on the D300.
The 12-24mm f/4G DX and 17-55mm f/2.8G DX are
somewhere between a 35mm lens and the 18-70mm DX lens
just mentioned: they have an image circle that covers the
35mm frame at some (but not all) focal lengths. In general,
these two DX lenses show slightly fewer edge problems than
the 17-35mm f/2.8D shows on a full frame 35mm body.
Likewise, uncorrected chromatic aberration or lack of flat
field focus capability may cause a lens to slightly soften the
corners of images when mounted on a 35mm camera. But
these issues are likely not as visible when using the D300. To
my eye, there is no discernable difference in optical quality
106 Chromatic aberration and light falloff, for example, increase with distance from the
center, and the D300 doesn't use the far edges of the image circle of regular 35mm
lenses. However, note that DX lenses have an image circle smaller than the 35mm
frame and may exhibit undesirable edge characteristics.
Thom Hogan's Complete Guide to the Nikon D300 Page 373