LensTip.com

Lens review

Sigma 30 mm f/2.8 EX DN

29 March 2012
Arkadiusz Olech

7. Coma, astigmatism and bokeh

On a small Micro 4/3 sensor the coma is corrected very well. The image of a diode positioned in the corner of the frame is only slightly distorted and in most cases this aberration won’t be bothersome at all.

Sigma 30 mm f/2.8 EX DN  - Coma, astigmatism and bokeh

The situation with astigmatism looks a bit more serious. At the maximum relative aperture it is really noticeable, reaching 13%. It decreases a bit on stopping down the aperture to f/4.0 getting to about 10% there. It becomes imperceptible only by f/5.6.


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 images of defocused diode, shown below, are hardly perfect too. The light is spread out in distinct ring shapes which suggest some mild problems with the spherical aberration correction.

Sigma 30 mm f/2.8 EX DN  - Coma, astigmatism and bokeh