Canon EF 50mm f/1.2 USM L - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

The EF 50mm f/1.2 USM L shows slight to moderate barrel distortion - a little more than its smaller cousins.

Note: the chart above has a real-world size of about 120x80cm.

Vignetting

Despite the reduced image circle of the EOS 350D the (full frame) lens exhibits quite pronounced vignetting (~0.9EV) at wide-open aperture. On full-frame DSLRs the problem should be even more critical. Nonetheless vignetting problems aren't all that unusual with ultra-large aperture lenses and on APS-C DSLRs the issue gets drastically reduced when stopping down a little. From f/2 onwards the issue is basically negligible.

MTF (resolution)

The EF 50mm f/1.2 USM L performed very well in the lab with some of the highest center resolution figures obtained on the 8mp sensor so far. The center resolution is already very decent at f/1.2 whereas the corners are less impressive although still "good". Beyond f/2 the center resolution is exceptional and probably a good deal better than the sensor resolution. The borders improve slowly till reaching their (excellent) maximum resolution at f/8. While this doesn´t give any reason to complain the substantially cheaper EF 50mm f/1.4 USM has a slightly better border performance.

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

Lateral Chromatic Aberrations (CAs)

Surprisingly the EF 50mm f/1.2 USM L is quite prone to lateral chromatic aberrations (color shadows at harsh contrast transitions). With an average CA pixel width beyond 1.2px the problem is unusually high for a fix-focal normal lens.

Longitudinal (Axial) Chromatic Aberrations (LoCA)

Similar to other ultra-large aperture lenses the Canon produces a substantial amount of LoCAs (non-coinciding focal planes of the various colors) at large aperture settings. Here´s an example at f/2.2:




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