Canon EF 70-300 mm f/4-5.6 IS II USM review - Coma, astigmatism and bokeh

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Canon EF 70-300 mm f/4-5.6 IS II USM

23 June 2017

Arkadiusz Olech

7. Coma, astigmatism and bokeh

The coma won’t be troublesome as long as you limit yourself to the APS-C sensor. In the corners of full frame, however, the situation is a bit different. In the 135-300 mm range that aberration is slight, with images of a diode just minimally deformed. More distinct deformations are visible at the shortest range of focal lengths and in that place exactly the coma will bother you the most, contributing significantly to the worsening of image quality.

Such an effect wasn’t observed in the case of the more expensive L-series lens but a very similar performance we saw during the tests of the Sigma 70–300 mm f/4–5.6 DG OS and the Tamron SP 70–300 mm f/4–5.6 Di VC USD.

Center, 70 mm, f/4.0	Corner APS-C, 70 mm, f/4.0	Corner FF, 70 mm, f/4.0

Center, 135 mm, f/5.0	Corner APS-C, 135 mm, f/5.0	Corner FF, 135 mm, f/5.0

Center, 200 mm, f/5.6	Corner APS-C, 200 mm, f/5.6	Corner FF, 200 mm, f/5.6

Center, 300 mm, f/5.6	Corner APS-C, 300 mm, f/5.6	Corner FF, 300 mm, f/5.6

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The astigmatism, understood as an average difference between horizontal and vertical MTF50 function values, amounted to just 3.0% so its level was low. It is the same result, within the margin of error, as the one of the more expensive L-series lenses, lower than that of both the predecessor and rival devices produced by independent companies.

Blurry area, generated by the tested lens, are blameless especially if you take into account the fact that you deal here with a moderately priced telephoto zoom. We found just two issues: a lighter rim on the edge of the circle and noticeable influence of mechanical vignetting.

Center, 300 mm, f/5.6	Corner APS-C, 300 mm, f/5.6	Corner FF, 300 mm, f/5.6

Center, 300 mm, f/8.0	Corner APS-C, 300 mm, f/8.0	Corner FF, 300 mm, f/8.0

Center, 300 mm, f/11.0	Corner APS-C, 300 mm, f/11.0	Corner FF, 300 mm, f/11.0