Canon EF 28-105mm f/3.5-4.5 USM - Review / Test Report - Analysis
Lens Reviews -
Canon EOS (APS-C)
Page 2 of 3
The lens shows slight barrel distortions at 28mm changing to slight pincushion distortions at the long end.
At around 40mm the level of distortions is negligible.
The chart above has a real-world size of about 120x80cm or 40x the focal length.
Expect more distortions towards closer focus distances.
Typical for full format lenses on APS-C DSLRs vignetting is no big issue thanks to taking advantage
of the sweet spot of the lens. It is unlikely that vignetting can be a problem even at wide-open
aperture but in super critical situations you may consider to stop down a little in order to eliminate the
remaining artifacts here.
The EF 28-105mm f/3.5-4.5 USM is fairly unexciting regarding resolution. The center performance is
decent throughout the range whereas the corners perform a little worse as usual - stopping down by
1 f-stop may be a good idea here. There're neither severe show-stoppers here nor is there something to rave about.
However, it is worth to mention that the tested sample had a slight decentering flaw visible at various settings -
nothing extreme but still clearly visible. Compared to fix-focals or L zooms the contrast performance
is also fairly low so you may miss an extra color kick at times.
Below is a simplified summary of the formal findings. The chart shows in line widths per picture height (LW/PH)
which can be taken as a measure for sharpness. If you want to know more about it you may check out the corresponding
Chromatic Aberrations (CAs)
Chromatic aberrations (color shadows at harsh contrast transitions) are a relatively minor
problem with this lens with an average pixel width of less than 1 pixel except at 28mm beyond f/8
(see also the left roof in the last sample shot below).