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Tamron AF 90mm f/2.8 SP Di 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 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.
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
very low and usually nothing to worry about.
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