LensTip.com

Lens review

Canon EF 24-85 mm f/3.5-4.5 USM

22 September 2007
Arkadiusz Olech

7. Coma and astigmatism

Canon’s coma correction is mediocre. At the wide aperture the coma is visible at every focal length, but at 85mm the result is acceptable.

Canon EF 24-85 mm f/3.5-4.5 USM - Coma and astigmatism


As far as astigmatism is concerned, its level averages 8.7%. The astigmatism is the least problematic in the middle of the focal length range and it is worst at the 85mm focal length, where it reaches 11%. We think that astigmatism is the main culprit for Canon’s weak resolution results.


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At this point we could ask the question whether the results would be better if the tested Canon was brand new and not a used one. The astigmatism is present when some of the optical elements bend toward the axis in the wrong angle. This situation can be blamed on overuse of the lens or the mechanical defects. There is still no answer to the question of whether the weak optical values at the 85mm focal length come with time and overuse or were there from the beginning.