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Lens review

Samyang 12 mm f/2.8 ED AS NCS Fish-eye

30 December 2014
Szymon Starczewski

7. Coma, astigmatism and bokeh

Looking at the crops below you might think that the coma in the corners of full frame is high. You have to remember that the stretching of the point-like image of a diode stems from more than one factor - not only the influence of the coma but also huge distortions present on the very edge of the frame makes itself felt.

Samyang 12 mm f/2.8 ED AS NCS Fish-eye - Coma, astigmatism and bokeh


The astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, amounted to 6.6%. It is a moderate value and it looks even better if you remind yourself that any fisheye lens is at a disadvantage when it comes to that particular aberration. Huge deformations of the image mean the resolution and astigmatism measuring areas are further away from the frame centre than in the case of classic lenses; it makes fisheye devices more prone to off-axis aberrations in turn.

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The appearance of defocused images doesn’t make us impressed. You see a lot of concentric rings and deformations. Still it is really difficult to get big, defocused areas with a fisheye lens.

Samyang 12 mm f/2.8 ED AS NCS Fish-eye - Coma, astigmatism and bokeh