Canon EF 50mm f/1.2L USM

Canon EF 50mm f/1.2L USM: Performance

At maximum aperture the sharpness in the centre is already good, but things aren't quite as clear towards the edges. This isn't a disaster for a lens like this, as the area in focus at f/1.2 will often be near the centre of the frame, isolated by the shallow depth of field.

Although the sharpness in the centre improves dramatically as the lens is stopped down, the resolution towards the edges remains relatively low. This lens is a specialist optic, to be used for effect, rather than an all-purpose lens that will be as at home on a copy-stand as it may be taking portraits. By f/4 the sharpness in the centre is outstanding and all images taken with this lens during testing have a unique look to them.

Resolution at 50mm		How to read our graphs The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on an Canon EOS 5D Mark II using Imatest.

At their most severe, chromatic aberrations cover an area of 1.1 pixel widths around high contrast edges. On a high resolution sensor, like that found on the EOS 5D MkII, this level should pose few issues, even at very large print sizes.

Chromatic Aberrations at 50mm		How to read our charts Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more. For this review, the lens was tested on an Canon EOS 5D Mark II using Imatest.

For a lens with such a large maximum aperture, falloff of illumination towards the corners is very well controlled. At f/1.2 the corners are only 1.5 stops darker than the image centre and visually uniform illumination is achieved by f/2.8.

Imatest detected 2.5% barrelling, which isn't an overly high level of distortion, but may pose issues for critical applications. However, this distortion is uniform across the frame, so it should be straightforward to correct in image editing software afterwards.

The deeply recessed front element is well-protected against extraneous light, even without the supplied circular hood attached, which makes the lens resistant to flare caused by light sources just outside the frame. When shooting directly into the light, contrast can drop quite severely, especially when shooting at maximum aperture.

Sharpnees is good in the centre at wide apertures - ISO100, 1/200. f/1.6, 50mm		Out of focus areas are smoothly rendered - ISO100, 1/125. f/2, 50mm
Stopping down results in outstanding sharpness in the centre - ISO100, 1/320. f/8, 50mm		The minimum focus distance of 45cm is typical for wide aperture 50mm lenses - ISO100, 1/320. f/8, 50mm
ISO100, 1/200. f/8, 50mm		ISO100, 1/250. f/8, 50mm
ISO100, 1/200. f/8, 50mm		ISO100, 1/160. f/11, 50mm

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