Viltrox AF 55 mm f/1.8 EVO
5. Chromatic and spherical aberration
Chromatic aberration
Contemporary standard f/1.8-2.0 lenses rarely have problems with the correction of longitudinal chromatic aberration. The Viltrox AF 55 mm f/1.8 EVO is not an exception here and, as you can notice in photos below, it deals with this kind of aberration very well. |
Now let's check the issue of lateral chromatic aberration – the performance depending on used detector and aperture value presents a graph below.
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There are no distinct differences between the edges of the APS-C/DX and full frame. In both cases aberration increases successively from near 0.01% at the maximum relative aperture to 0.03-0.04% for apertures ranging from f/5.6 to f/16.
It would be difficult to find any reason to worry – all values, measured by us, fit a level we consider to be very low. The Viltrox once again should be praised.
When it comes to comparison with the competition, the Nikkor Z 1.8/50 showed slightly better results, the Sigma C 2/50 and the Sonnar 1.8/55 FE performed very similarly, while the Panasonic S 1.8/50 performed the worst.
| A7R IIIa, RAW, f/1.8 | A7R IIIa, RAW, f/8.0 |
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Spherical aberration
In the first photos of this chapter you can notice a slight focus shift effect. As you stop down the aperture the depth of field seems to shift towards greater distances.You can also notice some influence of this aberration in the spread of light in out-of-focus circles of light we got before and behind the focus. Both circles have a slightly accented rim but in the case of the latter this rim is a bit brighter.
On the other side, the Viltrox offers you excellent resolution up from the maximum relative aperture, without any traces of contrast loss or slight mist, typical for instruments with badly corrected spherical aberration. Finally we can state that the influence of this aberration on the performance of the tested lens is medium at most.
| A7R V, f/1.8, before | A7R V, f/1.8, after |
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