LensTip.com

Lens review

Sigma A 35 mm f/1.2 DG DN

11 September 2019
Arkadiusz Olech

7. Coma, astigmatism and bokeh

The f/1.2 aperture and a wide angle of view are pretty demanding when it comes to coma correction. The Sigma's constructors didn't manage to control that aberration completely well because in the corners of full frame the image of a diode is a bit deformed; still that effect is slight and, taking into account the degree of difficulties, overall, I suppose, we shouldn't complain.

Center, f/1.2 Corner APS-C, f/1.2 Corner FF, f/1.2
Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh
Center, f/1.7 Corner APS-C, f/1.7 Corner FF, f/1.7
Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh


Astigmatism, understood as an average difference between horizontal and vertical MTF50 values, amounted to 7.5%. It's a moderate level which shouldn't worry you. It's worth noticing that the aberration will be visible mainly by f/1.2 and f/1.4; by f/2.0 it becomes practically imperceptible.


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

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

Defocused circles of light look good but we have some reservations concerning two things. Firstly, aspherical elements in the construction caused a slight onion ring bokeh effect. Secondly, and a far more important problem, we noticed mechanical vignetting and cropping of circles in frame corners, an effect which, by f/1.2, is really significant. How does it influence brightness loss in the frame corners? That question will be answered in the next chapter.

Center, f/1.2 Corner APS-C, f/1.2 Corner FF, f/1.2
Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh
Center, f/1.7 Corner APS-C, f/1.7 Corner FF, f/1.7
Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh
Center, f/2.5 Corner APS-C, f/2.5 Corner FF, f/2.5
Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh Sigma A 35 mm f/1.2 DG DN - Coma, astigmatism and bokeh