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Nikkor AF 50mm f/1.8 D - Review / Test Report - Analysis |
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Lens Reviews -
Nikon / Nikkor (APS-C)
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Page 2 of 3
Distortion
As expected for a fix-focal lens the level of (barrel) distortion is very low (0.26%)
and nothing to worry about.
The chart above has a real-world size of about 120x80cm. Possibly things may get a little
worse with extreme close-ups.
Vignetting
Thanks to the sweet spot behavior on the D200 vignetting is very well controlled.
Wide-open vignetting is a little stronger at ~0.66EV which may be visible in
very critical scenes. From f/2.8 and up the problem is negligible.
MTF (resolution)
Update 04/11/2006 - tested new sample which performed better at the borders.
Standard lenses are stellar performer when used at medium aperture settings
and the Nikkor AF 50mm f/1.8 D is no exception here. At f/4-f/8 the lens
is surely as good as it gets on the D200 with an excellent center
and a very-good border performance. Nonetheless it is also fairly typical
for ultra-large aperture lenses that things aren't quite as rosy at wide-open aperture but
the center is already excellent here whereas the borders are a bit soft
(combined with rather low contrast). From f/2.8
and up the distribution of the MTF50 curve suggests that the center performance
exceeds the quality of the D200. The borders improve continuously with good
figures at f/2.8 and very-good results at f/4.
The lens showed slight residual spherical aberrations (focus shift when stopping down).
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Chromatic aberrations (color shadows at harsh contrast transitions) are relatively
pronounced for a fix-focal with an average pixel width of 1.2px at the image borders.
Nonetheless it´s not a major problem. Stopping down improves the issue to moderate
figures.
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