Tamron AF 90mm f/2.8 SP Di 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 and infinity focus. From f/4 & up it is absolutely negligible. At 1:1 the problem is already non-existent at max. aperture.

MTF (resolution)

Typical for most macro lenses the Tamron AF 90mm f/2.8 SP Di macro performed very good to excellent in the lab. The lens is already very good in the center at wide-open aperture with marginally worse corners. The lens reaches its peak performance at f/5.6 where is scratches the resolution limits of the 8 mega pixel sensor of the EOS 350D. Beyond f/8 diffraction is the limiting factor - a physical barrier where no smart lens design can help. Generally you should avoid stopping down beyond f/16.

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 very low and usually nothing to worry about.




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