LensTip.com

Lens review

Sigma 70-200 mm f/2.8 EX DG APO OS HSM

6 September 2010
Arkadiusz Olech

7. Coma and astigmatism



Please Support Us

The coronavirus crisis has been adversely affecting many businesses and, sad but true, ours is not an exception. Despite that difficult situation we would like to preserve continuity and high quality of publications available on all our websites. Still, we are now aware it might be impossible without additional financial help. That's why we would like to ask all those who visit, read, and care about Optyczne.pl, LensTip.com i Allbinos.com for support - it's enough you send us a small sum of money via PayPal. If a lot people decide to support our websites we think we'll stand a chance and survive next months without any lasting harm. We count on your support and understanding, stay safe and be healthy.

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

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

The Sigma 70-200 mm OS corrects the coma very well. At 135-200 mm you can hardly notice any influence on the image of the diode and it is true for the APS-C/DX frame corner and full frame alike. Very slight coma can be noticed only after attaching the converter in the full frame corner at 70 mm so in a place where the resolution of a lens suffers the most.

Sigma 70-200 mm f/2.8 EX DG APO OS HSM - Coma and astigmatism

We mentioned astigmatism in the chapter about the lens’s resolution. It has a noticeable growth tendency with the increase of the focal length and it increases sharply after attaching the converter. At 70 mm its value is still negligible amounting to just 2%. At 135 mm it reaches a not very bothersome but already visible level of 10%. At 200 mm its level is not much higher, because 11%, but here it features an unpleasant property of being visible even after a significant stopping down. However real problems start only after you put the converter on because then the astigmatism level rises to a high level of 21%.