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Sigma AF 50mm f/2.8 EX DG macro - Review / Test Report - Analysis |
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Lens Reviews -
Canon EOS (APS-C)
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Page 2 of 3
Distortion
As to be expected from a fix-focal lens and especially for a macro lens the level of
distortion is absolutely negligible.
The chart above has a real-world size of about 120x80cm.
Vignetting
On the EOS 350D with its reduced format (APS-C) the (full format) lens exhibits very
little vignetting at f/2.8. From f/4 & up the issue is pretty much negligible. There's
even less vignetting at 1:1 macro setting compared to infinity focus.
MTF (resolution)
Macro lenses are generally no-brainers and the AF 50mm f/2.8 EX macro DG is no
exception. At f/2.8 the resolution figures are already very-good
increasing further to medium aperture settings where the quality scratches the
resolution limits of the 350D's 8MP sensor. Beyond f/8 diffraction is the limiting
factor but the resolution is still very decent at f/22. The lens provides
a f/45 setting but it's really nothing you want to use due to smeared
image details (this is a normal behaviour).
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Similar to most other fix-focal lenses chromatic aberrations (color shadows at harsh
contrast transitions) are exceptionally very and nothing to worry about.
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