LensTip.com

Lens review

Sigma 12-24 mm f/4.5-5.6 II DG HSM

27 December 2011
Arkadiusz Olech

7. Coma, astigmatism and bokeh

As long as you work on a small APS-C/DX sensor the coma won’t be bothersome. More problems you will be able to notice in the corners of full frame, especially at the shortest focal length. Fortunately even there the coma is not especially high - rather close to a medium level.

Sigma 12-24 mm f/4.5-5.6 II DG HSM - Coma, astigmatism and bokeh

Similar things can be said in the case of astigmatism. Its level is perhaps not the lowest but the value of 9% shouldn’t worry us excessively.

The photos below show us the blurry images of a diode, positioned in different places of the frame. The effect of using only six diaphragm blades is distinct; also sharp concentric circles prove that the spherical aberration is not corrected completely well.


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Sigma 12-24 mm f/4.5-5.6 II DG HSM - Coma, astigmatism and bokeh