Lens review

Nikon Nikkor Z 20 mm f/1.8 S

17 July 2020
Maciej Latałło

8. Vignetting

First let's check the vignetting performance on the smaller APS-C/DX sensor – appropriate thumbnails, prepared in crop mode with the help of the Nikon Z7, you can find below.

Nikon Z7, APS-C/DX, f/1.8 Nikon Z7, APS-C/DX, f/2.0
Nikon Nikkor Z 20 mm f/1.8 S - Vignetting Nikon Nikkor Z 20 mm f/1.8 S - Vignetting

There are some chances to notice vignetting but only in area close to the maximum relative aperture. By f/1.8 that aberration reaches a moderate level of 29% (−0.99 EV). On stopping down the aperture to f/2.0 it decreases to 24% (−0.80 EV), and by f/2.8 it becomes almost imperceptible, dropping to a value of 14% (−0.43 EV).

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After passing to a bigger full frame sensor there are far more problems – let's glance at photos below to assess the situation in more detail.

Nikon Z7, FF, f/1.8 Nikon Z7, FF, f/2.0
Nikon Nikkor Z 20 mm f/1.8 S - Vignetting Nikon Nikkor Z 20 mm f/1.8 S - Vignetting
Nikon Z7, FF, f/2.8 Nikon Z7, FF, f/4.0
Nikon Nikkor Z 20 mm f/1.8 S - Vignetting Nikon Nikkor Z 20 mm f/1.8 S - Vignetting

At the maximum relative aperture you have to deal with brightness loss in frame corners of as much as 57% (−2.47 EV). Here the tested lens fares a tad weaker than its reflex camera equivalent which vignetting level amounted to 49%.

When you stop the aperture down to f/2.0 vignetting decreases to a still high level of 53% (−2.17 EV). It remains quite noticeable also by f/2.8 where we got a result of 36% (−1.31 EV). A level closer to moderate values you can achieve only by f/4.0, where that aberration amounts to 30% (−0.82 EV). What's interesting, further stopping down doesn't have a measureable influence on the aberration, described in this chapter.

Nikon Z7, JPEG, f/1.8
Nikon Nikkor Z 20 mm f/1.8 S - Vignetting
Below we present averaged out values of brightness loss shown in concentric circles as you move further away from the frame centre. The numerical value of every image, expressed in percents, shows an area limited from the top and right by a value of 100% and from the bottom by the presented curve. The area indicates how much light overall is lost due to the vignetting effect. Please, don’t mix these percentages with the values given at the beginning of the chapter because they aren’t directly connected.

Nikon Nikkor Z 20 mm f/1.8 S - Vignetting

f/1.8 f/2 f/2.8 f/4