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The lens shows a moderate amount of barrel distortion on a DX camera.
The chart above has a real-world size of about 120x80cm.
On a DX camera the Nikkor shows slightly pronounced vignetting wide open, which is reduced to practically irrelevant levels by stopping down.
The lens delivers very good resolution in the image center at large apertures, which increases to excellent figures by stopping down to f/5.6 or f/8.
The image borders and corners are rather soft wide open. Stopping down lifts the resolution a little, but the lens never gets beyond good figures at the image borders and just fair values at the extreme corners.
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
Chromatic Aberrations (CAs)
Chromatic aberrations (color shadows at harsh contrast transitions) are moderate at large apertures, but increase considerably by stopping down.
Note that CAs can be corrected in software or by the camera itself (most modern Nikon DSLRs remove CAs themselves if you shoot JPGs). However, with values that high, CAs will have an influence on perceived sharpness, even if the colour cast at contrast edges can be easily removed.
A wide angle prime is certainly not primarily designed to throw the background out of focus (to the contrary, actually). However, with its ability to focus rather close, combined with the large aperture, the lens is able to separate the main subject from the background (at least for larger subject-to-background distances). So, let's have a quick look at the bokeh quality.
Out of focus areas show some nervousness and doubled contures. Background highlights are quite distorted towards the image borders at f/2.8 and f/4, but circular at f/5.6. Quite strong outlining increases the overall unpleasant character of the lens' bokeh.
You can find some sample images taken with the Nikon D3x in our Nikon FX review of the lens.
VerdictThe Nikkor AF-D 24mm f/2.8 shows very good to excellent sharpness in the image center. The borders and corners are quite soft wide open and benefit only slightly from stopping down.
Distortion moderate and vignetting no issue, except wide open. CAs are very pronounced stopped down, but can be taken care of in post-processing.
The build quality is very good. Unfortunately the lens has no internal motor, which means it doesn't autofocus on Nikon's entry-level DX cameras.
Despite the optical flaws, the lens may still be attractive for those who want to travel light, since it is quite compact and not very heavy.