Certain lenses with a very large maximum aperture, such as the EF 50/1.2L, exhibit focus shift. One way to compensate for this phenomenon is to focus while activating DOF preview, from f/1.4 - f/2.8, and sometimes down to f/4.
Certain lenses with a very large maximum aperture, such as the EF 50/1.2L, exhibit focus shift. One way to compensate for this phenomenon is to focus while activating DOF preview, from f/1.4 - f/2.8, and sometimes down to f/4.
Originally Posted by wickerprints
What happend to my post? How do I use this!? Heck. If I was able to do that, I would have kept my EF 50/1.2L.... Cripes.... I've got 30d and 5d, so no preview available, but if I could view it with the actual aperture (and the autofocusing still worked), even if the light is lower, that would have been great...
Still would be handy, particularly for Macro stuff..
As far as I am aware, every EOS body ever made supports DOF preview.
However, when I mean focus while stopped down, you must do this manually. AF does not operate while DOF preview is enabled. The use of a split prism focusing screen, or a super-precision matte screen assists in this task.
The problem with focus shift is that it is independent of AF or MF. For example, if you manually focused at f/1.2, then took the photo at f/2, you would still observe focus shift. In other words, it is not due to the inability of the camera to acquire accurate focus, but rather it is the optical design of the lens (i.e., undercorrected spherical aberration) that causes the problem.
There are other ways of dealing with focus shift. See here:
http://toothwalker.org/optics/spherical.html
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