Olympus M.Zuiko Digital 8 mm f/1.8 ED PRO Fisheye
5. Chromatic and spherical aberration
Chromatic aberration
The photos presented below show clearly that the Olympus 1.8/8 doesn’t have any problems with the correction of longitudinal chromatic aberration - even at the maximum relative aperture its level is very low.
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A bit more troubles you can encounter in the case of the lateral chromatic aberration and the graph below shows it well.
At the maximum relative aperture the results approach 0.1% and on stopping down they decrease. From f/4.0 the aberration becomes stabilized on a level of 0.08% or so. It shouldn’t make you worried because those results can be placed on a borderline between medium and low levels.
| Olympus E-PL1, f/1.8 | Olympus E-PL1, f/5.6 |
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Spherical aberration
The depth of field provided by the Olympus 1.8/8 is so significant that it would be difficult to say whether there is a focus shift effect or not. It seems the lens doesn’t experience any noticeable issues.
Still the appearance of the circles of light we got in front of and behind the focal point proves not everything is at it should be. The first circle features a distinct rim, the second one has a slight brightness loss. It means the spherical aberration is not corrected in a perfect way.
| Olympus E-PL1, f/1.8, in front of | Olympus E-PL1, f/1.8, behind |
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