LensTip.com

Lens review

Canon EF 20 mm f/2.8 USM

12 April 2010
Szymon Starczewski

7. Coma and astigmatism


- - - - - - - - - - - - - - - - - advertisement - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The coma in the tested lens is low but noticeable because an image of a diode is turned from a point into a comma in the frame corner. What’s interesting on stopping down by one stop we don’t see any decrease of this aberration.

Canon EF 20 mm f/2.8 USM - Coma and astigmatism

The tested lens controls astigmatism very well for a change because the average difference between vertical and horizontal MTF50 function values in the frame centre amounts to only 3%.