Leica APO-Summicron-SL 75 mm f/2 ASPH.
5. Chromatic and spherical aberration
Chromatic aberration
APO letters in the name of a lens oblige it to perfect correction of both types of chromatic aberration. Photos below show clearly that the tested Leica doesn't have any significant problems with the longitudinal variant of this aberration – you can notice very slight colouring in the out-of-focus areas positioned very far away but it's an effect that would be very difficult to see in real life photos so nothing to worry about. |
Even a better performance we notice in case of lateral chromatic aberration, and a graph below shows it very clearly.
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To be honest we haven't seen such perfect results for a very long time. At every combination of position in a frame and aperture value we got results below 0.01%. It means that, within the margin of measuring error, they are practically zero. The APO letters in the name of this lens are completely deserved – a round of applause!
| S1R II, 75 mm, RAW, f/2.0 | S1R II, 75 mm, RAW, f/4.0 |
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Spherical aberration
First photos from this chapter don't show any noticeable focus shift effect. What's more, defocused circles of light we got before and behind the focus look very much the same. The only thing you can notice is a tad brighter rim of the circle before the focus. Both these facts, along with excellent image resolution already from f/2.0, allow us to say that the tested APO-Summicron-SL doesn't have practically any problems with correction of spherical aberration.
| S1R II, 75 mm, f/2.0, before | S1R II, 75 mm, f/2.0, after |
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