Voigtlander Ultron 27 mm f/2
5. Chromatic and spherical aberration
Chromatic aberration
A very simple optical construction, devoid of any low dispersion glass elements, and a sensible aperture fastness suggested at once that you could encounter some problems with correction of longitudinal chromatic aberration. Still the Ultron performed here very well and we didn't notice any issues in this area. It was a really nice surprise. |
Now let's check the correction of lateral chromatic aberration – an appropriate graph can be found below.
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As you see, there are no reasons to complain. The aberration increases on stopping down the lens but, as it starts from a negligible value near 0.01%, even after the increase it reaches just the borderline between low and very low levels. Here also the small Ultron should be praised.
| Fujifilm X-T2, RAW, f/2.0 | Fujifilm X-T2, RAW, f/16.0 |
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Spherical aberration
In the first photos of this chapter you can't notice any 'focus shift' effect. When it comes to defocused circles of light we got before and behind the focus they are hardly identical but, at the same time, the differences between them aren't huge. Taking it all into account you can say that spherical aberration is not a huge problem of this simple optical system, another very nice surprise.
| Fujifilm X-T2, f/2.0, before | Fujifilm X-T2, f/2.0, after |
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