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The SLR Magic lens produces a moderate degree of barrel distortion (~1.26%) which is barely an issue in field conditions and still very good for a wide-angle lens.
At large aperture settings like f/1.6 a lens is almost doomed to produce a heavy light fall-off towards the border of the image field. Consequently the issue is very visible at around ~1.9EV (f-stops) and you have to stop down at least to f/5.6 to reach a moderate degree of vignetting below 1EV. The issue is not auto-corrected by the camera.
The following image illustrates the above mentioned vignetting from f/1.6 to f/8.
Ultra-large aperture lenses tend to be rather soft at maximum aperture. The SLR Magic Hyperprime manages to deliver a very good center and border performance at f/1.6 whereas the corners are slightly softer. Stopping down to f/2.8 shows already an excellent center as well as a pretty good outer image zone but the sweet spot is reached around f/4 with the highest center-border-corner quality. Due to diffraction you should not stop down past f/8.
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
The following figures shows a crop of the image center at apertures from f/4 and f/8. Starting at f/5.6 the sharpness drops at a certain small spot clearly noticeable below 1200 LW/PH. It's hard to imagine the origin of this issue but according to SLR Magic caused by lens flare.
Chromatic Aberrations (CAs)
Lateral CAs (color shadows at harsh contrast transitions) are a slight weakness of the SLR Magic Hyperprime. These color shadows are visible throughout the whole aperture range with an average CA width of around ~1.2px at the image borders. The issue is not auto-corrected by the camera.
Large aperture lenses not only tend to be rather soft at maximum aperture but are also prone to annoying lens flare. The SLR Magic Hyperprime is no exception here but stopping down to f/2.0 helps already. The following figure shows this issue at wide open.
If you move your mouse cursor over the image you can switch to the corresponding result at f/2.0.