Sharper autofocusing
Refine focus for your camera and lenses with micro focus adjustments
Canon first introduced micro focus adjustment capability on the EOS-1D Mark III. The intention was to provide photographers with a method to be able to compensate for slight focus errors, that can arise after a lens, or camera, takes a knock. If you’re on a remote photography trip this could be helpful until you can get the kit serviced.
Some photographers find that micro focus adjustments improve their focus accuracy, and have taken to checking out each lens. In theory, there should be no need for micro focus adjustment, but it is possible that with manufacturing tolerances there might be some benefits – particularly with older lenses on the latest cameras. There are two kinds of adjustment, one for the camera and one for a specific lens. If your camera consistently focuses in behind, or front of your
subject with all lenses then it’s a body adjustment you need. More commonly a specific lens adjustment is used.
Some companies make hardware and software tools to help calibrate your camera and lenses. I used Reikan Focal Pro to check some of my lenses on one of my cameras. The software is easy to use, and guides you through the steps to setup the camera and test target. Once the target and camera is setup, the process is largely automated with the software controlling the camera. You just need to make some changes to the AF microadjust values on the camera as the test progresses. Zoom lenses have two settings, one for the wide-angle and one for the telephoto zoom position. The camera will ramp between the two settings for intermediate focal lengths.
If your camera misses focus, and does not have micro focus adjustment,
you can ask Canon service to calibrate the camera and lens. The cost is approximately £40 per camera or lens. There’s a handful of main Canon service centres that have a special AF calibration machine created by Canon in Japan, there is one in Canon UK’S Elstree service centre.