Sigma AF 50mm f/2.8 EX DG macro - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

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).

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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