Lens review
2012-04-18
Sigma 70 mm f/2.8 EX DG Macro
7. Coma and astigmatism
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The Sigma 2.8/70 can be liked also because its coma correction - it is simply exemplary. The traces of that off-axis aberration would be difficult to spot even when the lens is wide open as you can notice in a photo, posted below.
It is not the end of going into raptures because the next of important off-axis aberrations, astigmatism, is also corrected in an exemplary way. The average difference between horizontal and vertical MTF50 values, measured near the frame centre (typically in the distance of 15-17% from the edge) amounted to just 2.7%.
