In-camera Lens Corrections

The Canon EOS 5D Mark III comes with optional in-camera optical corrections which Canon calls 'Lens aberration correction' in the menu. Peripheral Illumination Correction and Chromatic Aberration Correction are available in the Shooting menu. If these features are enabled the camera will attempt to reduce the respective effects based on Canon's profiles of current lenses. Even though lens compensation will be applied to the JPEG file when shooting in raw+JPEG, the raw file will remain uncompensated.

Peripheral illumination (vignetting) and Chromatic aberration correction can be enabled in the camera's shooting menu.

Distortion correction, on the other hand, can only be applied during in-camera Raw conversion after shooting. This is a step forward from the 5D Mark II where distortion correction could only be applied in Canon's DPP software, but ideally you'd have the option to enable distortion correction for JPEG images.

Distortion correction

As you can see in the images below, distortion correction does a very good job of keeping the image from showing the barrel distortion caused by the lens. This shot was taken with the EF 24-105mm F4 L lens at its widest focal length. The sample was shot as Raw+JPEG, and we then converted the Raw file in-camera to apply distortion correction.

When examining the corrected images there is a touch of corner softness which is almost certainly a consequence of the correction process, but overall the distortion correction is doing an excellent job, eliminating a large portion of distortion with only a minimal loss of quality at the edge of the frame.

Distortion Correction On
Distortion Correction Off

CA compensation

When activated in the menu CA correction does a good job of removing fringing as you can see in the the sample crop below. This image was taken with the EF 24-105mm F4 L lens but each lens will have its own particular CA characteristics. Therefore results will vary with the lens you use.

CA Correct On
CA Correct Off

The rollover above shows a 100% crop. The click-through links to the full image. This feature is enabled by default and we imagine most people will leave it enabled, as there is really no noticeable detriment to overall image quality or continuous shooting speed.

Peripheral illumination correction

The following vignetting (peripheral illumination) correction analysis was shot using the EF 24-105mm F4 L lens, at the widest focal length and F4. As you can see in the samples below the correction function is quite effective at reducing vignetting.

Vignetting Correction On
Vignetting Correction Off

With the feature enabled the far corners of the frame retain 55% of the center brightness. When shading compensation is off the brightness drops to 22% of center brightness. Although the compensation does not remove all of the vignetting caused by the lens, it will make a noticeable difference, especially in images with large areas of continuous tone, as you might find in bright skies. And even though peripheral illumination correction works by essentially increasing the brightness in the corners of the image, we don't see a significant increase in visible noise in the compensated areas.