Some of the modern Canon EOS digital cameras have built an AF micro adjustment, which you optimally adjust the auto focus of all lenses to avoid front or back
focus. Unfortunately, it is a fact that even brand new lenses are subject to the top price range of a certain series of scattering. Since then only the direct service helps the Canon
CPS with adjustment of the lenses on the camera.
To correct small variations of static auto-focus cameras, 7 d, 5 d mark have some EOS II, and the whole 1 d series in the professional segment the built-in
possibility on the C.Fn. - AF fine adjustment to adjust the auto focus.
There are many methods to perform these AF adjustment, one of I've tried on my lenses for EOS cameras with live view and am very pleased with the results. If
you would like to try it can download Guide to the micro adjustment here as PDF File.
Have fun in testing.
Addition to the micro adjustment with live view.
Since a couple of questions have surfaced which I would like to answer here even complementary.
The quick shot is actually in live view mode a mix between measuring with the phase sensor of live view and trigger the recording of but then again the normal AF system of the camera with lens attacks.
The EOS utility is a tool and no software to the lens adjustment. The tool does not take over the manually corrected value from the micro adjustment of the camera. Therefore also the AF are on every pass again and again visible differences between quick shot phase sensor and focus point of the lens in live view.
In the owner's Manual of the cameras with live view (here to the 5DII) said: Quick AF mode: Focuses on the AF sensor specially developed in the one-shot AF mode with the same AF mode such as for live image recording. (I.e. phase sensor) You can quickly focus the target range, the live image is however briefly interrupted during the AF focus.
No question is that when live view regardless of a false focus of the lens the optimal sharpness in an image is achieved with the Phasensenor. Therefore you can almost see the quick shot phase sensor in this method as a reference point to the focus point of the lens. So, the procedure described is to determine whether and in what order of magnitude is a false focus. Visually found must then be entered in the MJ of the camera per lens. I have my lenses and zooms so once measured and adjusted and am very satisfied with this method. It is especially in the zoom also good times to see how different is the focus in the different areas of focus.