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Distortion
On a DX camera, the lens shows only a minor amount of barrel distortion.
The chart above has a real-world size of about 120x80cm.
Vignetting
Typical for many FX lenses when used on DX cameras, vignetting is no issue. Even at the largest aperture, the amount of light fall-off towards the borders is only minor.
MTF (resolution)
The lens shows excellent resolution in the image center wide open already and remains on this high level down to f/8. At f/11 (and beyond) diffraction takes its toll and significantly reduces resolution again.
The borders and corners follow one step behind with very good resolution across the tested aperture range.
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 quite low and well controlled wide open, but increase to higher levels when stopping down. However, CAs can easily be corrected in software or by the camera itself (most modern Nikon DSLRs remove CAs themselves if you shoot JPGs).
Bokeh
One of the primary usage scenarios for a large aperture lens is to seperate the main subject from the background. In such an image the quality of the bokeh (out-of-focus blur) is of major significance.
The background blur shows some signs of nervousness in the transition zone from in-focus to out-of-focus, but apart from that is generally quite smooth.
Background highlights show only a very small amount of outlining and are actually well rendered. However, they are slightly condensed towards the image borders due to mechanical vignetting and start to lose their circular shape at apertures of f/5.6 and smaller. In addition, there's a visible amount of bokeh fringing (green outlines, see next section).
Bokeh Fringing
Bokeh fringing is a common issue with relatively fast glass. It's visible as halos of different colors in out-of-focus areas - magenta (red + blue) in front of the focus point
and green beyond.
Typical for most fast primes the AF-D 180 shows noticeable bokeh fringing at large aperture settings, which can of course be reduced by stopping down.
Flare/Glare
The lens does not really like backlight and visibly loses contrast across the whole image in these conditions. In addition to the glare, there are also traces of soft flare spots, but depending on the subject they may not be visible at all. IN the sample image below, you can see a green haze spot close to the lower border of the image.
Sample Images
You can find some sample images taken with the Nikon D3x in our Nikon FX review of the lens.
VerdictThe AF-D 180/2.8 performs on a very high level. Center resolution is excellent wide open already, while the borders and corners show very good sharpness throughout the tested aperture range. Typical for many FX lenses when used on DX cameras, distortion and vignetting are very low. CAs are moderate and well controlled wide open, but increase when stopping down.
Bokeh is generally quite smooth, except for the transition zone, but many lenses struggle in this area. As most fast primes, the AF-D 180 shows a significant amount of bokeh fringing at large apertures.
Typical for professional grade lenses, the build quality is excellent, except for the somewhat fiddly AF/MF switch.
So, in summary it's a nice and (comparatively) light-weight option to the high end f/2.8 tele zooms, at least for those who do not need the flexibilty of the zoom and mostly live on the long end of the 70-200mm range anyway. It is, however, not a cheap lens, especially since it a somewhat dated design nowadays. This is also reflected in the going price for used units, which is considerably lower than the current retail price.
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