|
Canon EF 85mm f/1.2 USM L - Review / Test Report - Analysis |
|
Lens Reviews -
Canon EOS (APS-C)
|
|
Page 2 of 3
Distortion
As expected for a fix-focal lens the level of distortion is negligible:
The chart above has a real-world size of about 120x80cm. Possibly things may get a little worse with extreme close-ups.
Vignetting
An ultra-large aperture lens is expected to vignette quite a bit and at f/1.2 you can indeed
see quite pronounced vignetting of about ~0.65 EV even on an APS-C DSLR like the EOS 350D. In many
cases this isn't a problem but it can be visible. It's quite save to assume that vignetting is
quite a bit more pronounced on an EOS 1D series camera due to the bigger image sensor.
On the EOS 350D and at f/1.8 the problem is already quite negligible and at f/2.8 it's basically
non-existent.
MTF (resolution & chromatic aberrations)
The lens performed OUTSTANDING in the lab and that's at ALL tested aperture settings.
At f/1.2 the results are already very good across the frame which is surprising for such
an extreme setting. The performance peaks at f/4-5.6 with resolution figures that
suggest that the limits of the 8mp sensor (EOS 350D) are the barrier for this lens.
The chromatic aberrations (CA) don't exceed an average of 0.68 pixels at the image borders so they're
quite low and usually no problem. The lens showed slight RSA (focus shift when stopping down -
the MTF chart was revised accordingly).
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
|
