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Lens review

Samyang 35 mm f/1.2 ED AS UMC CS

26 November 2018
Maciej Latałło

7. Coma, astigmatism and bokeh

Coma is not corrected in a perfect way and noticeably deformed images of a diode in photos are the proof. On the other hand the results are much better than those of many older classic 50 mm f/1.4–1.8 devices which sometimes performed abysmally bad in this category.

X-T2, f/1.2, center X-T2, f/1.2, corner
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh
X-T2, f/1.7, center X-T2, f/1.7, corner
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh


Similar images can be observed not only during a studio photographic session but also outside, when you point the lens at the starry sky. Coma still makes itself felt and stars are deformed in frame corners but the level of these deformations can be still described as medium.

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Fujifim X-T2, JPEG, f/1.4, corner of the frame 1:1
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh

Astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, reached 17.6%. It is a significant result. It’s clear that the astigmatism, next to spherical aberration, contributes significantly to the worsening of image near the maximum relative aperture.

When it comes to defocused circles of light their appearance is hardly perfect. First of all you can notice distinct concentric circles, most likely a result of using aspherical elements. There’s also noticeable truncation of circles in the frame corner caused by mechanical vignetting. Fortunately the outer rim is not bothersome almost at all.

X-T2, f/1.2, center X-T2, f/1.2, corner
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh
X-T2, f/1.7, center X-T2, f/1.7, corner
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh
X-T2, f/2.4, center X-T2, f/2.4, corner
Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh Samyang 35 mm f/1.2 ED AS UMC CS - Coma, astigmatism and bokeh