1. Mount the camera and lens on a tripod. If the lens has IS, shut it off.
2. Use Live View to manually focus on a stationary, flat, high-contrast object that is at the center of the viewfinder and parallel to the plane of focus. The camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens this would be approximately 8.2 feet.
3. Focus the lens at its maximum aperture. Use Live View magnification if necessary to assure that the image is as sharp as possible.
4. Without touching the focusing ring or moving the tripod, turn off Live View, and return the camera to One-Shot AF, using only the center AF point.
5. Gently press the shutter button down halfway while observing the focusing ring or scale on the lens. It should not move. If it does, take note of whether AF moves the plane of focus closer (front-focus) or further away (back-focus). If there is no shift in focus your lens is well-calibrated and requires no adjustment.
6. To determine the correct amount of adjustment necessary, take three sets of images at microadjustment settings of -10 , 0 and +10; in other words, three consecutive images at -10, three consecutive images at 0, and three consecutive images at +10.
7. Examine the resulting images on your computer monitor at 100% pixel magnification.
8. Take additional sets of test images at different microadjustment settings if necessary until you can determine which setting produces the sharpest image.
9. Register the corresponding microadjustment setting in the camera.
Remember: for AF Microadjustment to work, there has to be some issue with your AF system's ability to render the intended plane of sharpest focus truly sharp. Whether you use AF or focus manually, sharp focus can only be in one of three places: either right on your intended subject, in front of that subject, or behind it. In other words, if focus is the problem, something in the picture usually looks tack-sharp. Here's the point: if you're seeing images where *nothing* looks critically sharp, you probably need to examine other possible issues. This includes camera or subject movement from too slow a shutter speed, the amount of electronic sharpening being applied to your files, Picture Style settings if you're shooting JPEG images, and so on. AF Microadjustment cannot account for these problems.
EB
EOS 1DX and 1D Mk IV and less lenses then before!
