Olympus M.Zuiko Digital ED 25 mm f/1.2 PRO
7. Coma, astigmatism and bokeh
E-M5 II, 25 mm, f/1.2, center | E-M5 II, 25 mm, f/1.2, corner |
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E-M5 II, 25 mm, f/1.8, center | E-M5 II, 25 mm, f/1.8, corner |
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The astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, amounted to 17.6%. It is a high value. What’s more that aberration is noticeable even at apertures ranging from f/2.8 to 4.0, one of the reasons why the tested lens didn’t manage to get to a level of 80 lpmm with its MTFs.
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Light discs we got in out-of-focus areas look nice. The light spreads evenly, without any distinct local extremes. You can notice two things, though. Firstly, on stopping down the aperture a lighter rim appears. Secondly, at the maximum relative aperture the disc has soft edges and the brightness loss in its upper area is a bit more pronounced than downwards. It might be connected to mechanical vignetting.
E-M5 II, 25 mm, f/1.2, center | E-M5 II, 25 mm, f/1.2, corner |
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E-M5 II, 25 mm, f/1.8, center | E-M5 II, 25 mm, f/1.8, corner |
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E-M5 II, 25 mm, f/2.5, center | E-M5 II, 25 mm, f/2.5, corner |
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