LensTip.com

Lens review

Sigma C 90 mm f/2.8 DG DN

8 November 2021
Maciej Latałło

7. Coma, astigmatism and bokeh

We complained about distortion, but we are going to praise coma correction for a change. Even in corners of full frame and at the maximum relative aperture diode images don't show almost any deformations. It seems coma has a negligible influence on worsening of image quality on the frame edges.

Center, f/2.8 Corner APS-C, f/2.8 Corner FF, f/2.8
Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh
Center, f/4.0 Corner APS-C, f/4.0 Corner FF, f/4.0
Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh


Astigmatism, understood as an average difference between vertical and horizontal MTF50 function values, amounted to 4.5 %. It's a very low value, not giving you any reasons to worry.


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Defocused circles of light look sensibly well. You can notice a slight trace of onion-ring bokeh and it stems from the fact that there is one aspherical element inside the optical stystem. On stopping down the aperture a rim appears on the edge of the circle but it is not especially intense. Mechanical vignetting is visible at the maximum relative aperture and on stopping down the lens by 1 EV; by f/5.6 it disappears completely.

Center, f/2.8 Corner APS-C, f/2.8 Corner FF, f/2.8
Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh
Center, f/4.0 Corner APS-C, f/4.0 Corner FF, f/4.0
Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh
Center, f/5.6 Corner APS-C, f/5.6 Corner FF, f/5.6
Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh Sigma C 90 mm f/2.8 DG DN - Coma, astigmatism and bokeh