Leica APO-Summicron-SL 35 mm f/2 ASPH.
5. Chromatic and spherical aberration
Chromatic aberration
APO letters in the name of this lens obligate to an excellent correction of two types of chromatic aberration. The crops below prove that the Leica doesn't have any slip-up in this category. Longitudinal chromatic aberration doesn't bother you practically at all. |
What about lateral chromatic aberration? An appropriate graph you can find below.
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Here the puzzle from the previous chapter is partially solved – I mean here a very similar performance on the edge of the APS-C sensor and on the edge of full frame. The chromatic aberration contributes to that phenomenon as it first increases and on the edge of the APS-C sensor it can reach 0.06%, and then it decreases and on the edge of full frame it keeps values close to 0.03%.
It's worth mentioning the fact that both levels don't provide any reasons to complain because the first is low and the second – very low. Of course for the comparison's sake you should mention here the perfect result of the APO-Summicron-SL 75 mm f/2 model, with aberration never exceeding 0.01%.
| S1R II, 35 mm, RAW, f/2.0 | S1R II, 35 mm, RAW, f/5.6 |
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Spherical aberration
First photos of this chapter show a slight focus shift effect. You don't see it as you change the aperture from f/2.0 to f/2.8 but it is already visible as you pass from f/2.8 to f/4.0. It can explain why the tested Leica performs perfectly well by f/2.0 and it doesn't break any resolution records by f/2.8 and f/4.0.Spherical aberration cannot be very high, as the defocused circles of light we got before and behind the focus are very similar.
| S1R II, 35 mm, f/2.0, before | S1R II, 35 mm, f/2.0, after |
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