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Lens review

Voigtlander Ultron 40 mm f/2 SL II Aspherical

9 November 2010
Arkadiusz Olech

7. Coma and astigmatism

Weak performance on the edge of the frame near the maximum relative aperture make us suspect that the Voigtlander, like many other relatively fast 35-50 mm lenses, has a lot of problems with the coma. One look at the crops below shows that it is really the case. In the corner of full frame at the maximum relative aperture the coma is simply huge. On stopping down by one stop we see it decreasing significantly but still it remains quite pronounced.

Voigtlander Ultron 40 mm f/2 SL II Aspherical - Coma and astigmatism

At the maximum relative aperture the coma is also visible in the corner of the APS-C/DX sensor but there we can describe it as medium at most. The aberration disappears almost completely by f/2.8.

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When it comes to the astigmatism, the problems somehow aren’t significantly less serious. The average difference between horizontal and vertical MTF50 values amounts to 12% which is a medium value.