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Lens review

Samyang 85 mm f/1.8 ED UMC CS

5 October 2018
Maciej Latałło

7. Coma, astigmatism and bokeh

Coma is not corrected perfectly well but we have no serious reservations to the performance of the lens either. In fact the only distinct feature we noticed are slightly enlarged images of a diode in the very corner of the frame but still its shape remained more or less circular. There is no elongation characteristic for coma, or additional “wings” connected to off-axis aberrations of higher degrees.

X-T2, f/1.8, center X-T2, f/1.8, corner
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh
X-T2, f/2.4, center X-T2, f/2.4, corner
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh


Similar images you can catch photographing the diode not only in the studio but also pointing the lens at the starry sky. Coma’s influence is very limited so the images of stars are not especially deformed, although some small influence of that aberration can still be noticed.

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Fujifim X-T2, JPEG, f/1.8, corner of the frame 1:1
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh
Fujifim X-T2, JPEG, f/2.0, corner of the frame 1:1
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh

Astigmatism, understood as an average difference between vertical and horizontal MTF50 values, reached 3.8%. It is a result we consider to be very low.

When it comes to defocused light circles and out-of-focus areas the tested Samyang seems to be beyond reproach (apart from distinct mechanical vignetting). The light spread in the circles is even, the lighter rim never makes itself felt and the aperture seems to be well rounded. A round of applause!

X-T2, f/1.8, center X-T2, f/1.8, corner
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh
X-T2, f/2.4, center X-T2, f/2.4, corner
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh
X-T2, f/3.4, center X-T2, f/3.4, corner
Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh Samyang 85 mm f/1.8 ED UMC CS - Coma, astigmatism and bokeh