Viltrox AF 27 mm f/1.2
5. Chromatic and spherical aberration
Chromatic aberration
When you join an angle of view of 55 degrees and the f/1.2 aperture the bar is set very high when it comes to the correction of longitudinal chromatic aberration. Viltrox optics specialists were fully aware of that so they larded the lens with optics elements made of different kinds of expensive glass. The final result? The tested lens doesn't have any problems in this category. Even at the maximum relative aperture it's difficult to get any noticeable colouring in out-of-focus areas positioned further away. |
Now let's check how the Viltrox AF 27 mm f/1.2 corrects lateral chromatic aberration – an appropriate graph you can find below.
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Once again you deal here with outstanding results because the level of this aberration doesn't exceed a truly negligible value of 0.02% at any aperture. Once again the tested lens deserves to be praised.
| Fujifilm X-T2, RAW, f/1.2 | Fujifilm X-T2, RAW, f/11.0 |
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Spherical aberration
In first photos of this chapter you can notice a slight focus shift effect. When you pass from f/1.2 to f/1.8 the depth of field shifts towards greater distances. Fortunately it is not a noticeable effect and it becomes even less conspicuous when you pass from f/1.8 to f/2.5.Defocused circles of light we produced before and behind the focus feature effects of a similar scale. The influence of slight spherical aberration can be noticed in a form of a soft edge in the first circle and a slightly brighter rim in the second one.
It's clear that the producers of the tested Viltrox didn't correct spherical aberration in a perfect way and left it on a medium level. Perhaps it was deliberate in order to ensure a better appearance of out-of-focus areas. The influence of this aberration is visible in our testing procedures but still the image quality at the maximum relative aperture is so high that spherical aberration cannot be very bothersome.
| Fujifilm X-T2, f/1.2, before | Fujifilm X-T2, f/1.2, after |
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