Carl Zeiss Batis 18 mm f/2.8
5. Chromatic and spherical aberration
The correction of the longitudinal chromatic aberration is more or less properly done. You can notice the colouring of out-of-focus images but its level is medium at most.
| f/2.8 | f/4 |
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Let’s check how the lens corrects the lateral chromatic aberration – the graph below shows our measurements for frame edges of APS-C and FF.
In this case the full frame results are higher than results we got on the edge of the APS-C sensor. The APS-C values range from 0.03 to 0.04% so the lateral chromatic aberration shouldn’t be visible in photos. On the edge of full frame that aberration level is slight, ranging from 0.05 to 0.06% but in specific cases the aberration might be a bit visible in photos. Overall the situation is good and the Zeiss deserves to be praised for it.
| A7R II, RAW, F/2.8, BRZEG FF | A7R II, RAW, F/2.8, BRZEG APS-C |
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Spherical aberration
The lens doesn’t have any „focus shift” effect and misty areas, so characteristic for badly corrected spherical aberration, are not especially visible at the maximum relative aperture. Additionally defocused circles of light created in front of and behind the focus aren’t identical. Tiny differences in the middle of them indicate the presence of vestigial spherical aberration; still it would be difficult to call its level high.
| A7R II, F/2.8, In front of | A7R II, F/2.8, behind |
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