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Lens review

Sony FE 20-70 mm f/4 G

17 January 2023
Maciej Lata││o

7. Coma, astigmatism and bokeh

Overall the Sony FE 20-70 mm f/4 G doesn't experience any visible problems related to coma. Even in the corners of full frame images of a diode aren't deformed no matter what focal length you use. The only effect that can be noticed is increasing size of the light point but it doesn't have to be connected with classic coma. It might also be an effect of e.g. curvature of field or optical aberrations of higher degrees.

Center, 20ámm, f/4.0 Corner APS-C, 20ámm, f/4.0 Corner FF, 20ámm, f/4.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh
Center, 35ámm, f/4.0 Corner APS-C, 35ámm, f/4.0 Corner FF, 35ámm, f/4.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh
Center, 50ámm, f/4.0 Corner APS-C, 50ámm, f/4.0 Corner FF, 50ámm, f/4.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh
Center, 70ámm, f/4.0 Corner APS-C, 70ámm, f/4.0 Corner FF, 70ámm, f/4.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh


Astigmatism, understood as an average difference between vertical and horizontal MTF50 function values, amounted to 3.4% and it is a very low level. It's also important that the lens's performance is very even in this category, without any meaningful differences between particular focal lengths. A round of applause!


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Defocused circles of light look sensibly well, especially if you take into account the fact that you deal here with a zoom lens with a significant zoom factor and truly unique parameters. Traces of onion ring bokeh are noticeable but only because you can find as many as four aspherical elements inside the lens's construction. A slight rim is also visible on stopping down. Also mechanical vignetting doesn't make itself felt – you can notice it mainly in the proximity of the maximum relative aperture.

Center, 70ámm, f/4.0 Corner APS-C, 70ámm, f/4.0 Corner FF, 70ámm, f/4.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh
Center, 70ámm, f/5.6 Corner APS-C, 70ámm, f/5.6 Corner FF, 70ámm, f/5.6
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh
Center, 70ámm, f/8.0 Corner APS-C, 70ámm, f/8.0 Corner FF, 70ámm, f/8.0
Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh Sony FE 20-70 mm f/4 G - Coma, astigmatism and bokeh