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Lens review

Yongnuo YN 50 mm f/1.8

26 January 2015
Szymon Starczewski

7. Coma, astigmatism and bokeh

The Canon 1.8/50 II corrected coma very well across the whole APS-C sensor but had much worse results in corners of full frame. The Yongnuo fares here even worse. The coma is visible even in the corners of the APS-C sensor but it doesn’t reach high levels. In the corners of full frame the situation is disastrous and the coma can be observed in all its glory.

Center, f/1.8 APS-C corner, f/1.8 Róg corner, f/1.8
Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh
Center, f/2.5 APS-C corner, f/2.5 FF corner, f/2.5
Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh


Weak resolution results near the maximum relative aperture are partially due to the astigmatism. The average difference between horizontal and vertical MTF50 values amounted to a high value of 22.8%. It’s also worth adding that the astigmatism of the Canon 1.8/50 II was visible only by f/1.8 and f/2.0 but the Yongnuo must be closed down to f/4.0 in order to eliminate that aberration completely.

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Seven diaphragm blades, featured by the Yongnuo, compared to five blades of the Canon make much difference. If you add to that a more or less even light spread in the circles the only problem which might bother you are truncated corners connected to the high vignetting level.

Center, f/1.8 APS-C corner, f/1.8 FF corner, f/1.8
Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh
Center, f/2.5 APS-C corner, f/2.5 FF corner, f/2.5
Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh
Center, f/3.5 APS-C corner, f/3.5 FF corner, f/3.5
Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh Yongnuo YN 50 mm f/1.8 - Coma, astigmatism and bokeh