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Lens review

Nikon Nikkor AF-S 20 mm f/1.8G ED

18 October 2014
Szymon Starczewski

4. Image resolution

The resolution test of the Nikkor AF-S 20 mm f/1.8G ED was based on RAW files from the Nikon D3x camera, with the decency level situated near 30-32 lpmm. Good quality fixed focus lenses, attached to that body, can reach as high as 47-49 lpmm and the record value belongs to the Zeiss Otus 1.4/55 which, by f/4.0, managed to exceed slightly a level of 50 lpmm.

Let’s check how the Nikkor 1.8/20 compares here – a graph below shows its performance in the frame centre, on the edge of the APS-C/DX sensor and on the edge of full frame.

Nikon Nikkor AF-S 20 mm f/1.8G ED - Image resolution

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When it comes to the frame centre the results are definitely very good. Already at the maximum relative aperture the image is sharp, with the MTFs getting near 35 lpmm. On stopping down the image quality improves noticeably and by f/4.0 it reaches the maximum value, amounting to 46 lpmm. It is not a record but still it’s worth your praise.

The edge of the APS-C sensor is beyond reproach as well. Even at the maximum relative aperture the image remains decent, improving slowly on stopping down and reaching the maximum MTF values near f/8.0. The results won’t perhaps bowl you over but certainly they are good, allowing you to enjoy sharp images.

Our reservations start on full frame but it is hardly a surprise. Small dimensions of the lens and its demanding parameters had to make themselves felt somehow. As a result you land below the decency level near the maximum relative aperture and sensible MTFs are reached only after stopping down to f/4.0-f/5.6.

To sum up, taking into account the scale of the problem the Nikon optics specialists were facing, the overall assessment of the tested lens is very positive. The image quality in the frame centre and on the edge of the APS-C sensor remains flawless. The problems appear only on the edge of full frame but even there the results are satisfactory after you stop the lens down a bit more.

The crops you see below were taken from JPEG files saved along RAW files we used for the analysis above.

Nikon Nikkor AF-S 20 mm f/1.8G ED - Image resolution