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p.1 #13 · p.1 #13 · What is the tolerance of Microadjustment on lenses? | |
sangdabom73 wrote:
Hello,
I have a question about microadjustment of lenses on 5d2.
All of my canon lenses are within +/- 2 or less on Microadjustment. However, my new Sigma 35mm f1.4 lens has +9. Is that too high? Is there any drawback of having high adjustment number?
Thank you for your help.
OK, here is the word directly from Canon:
http://learn.usa.canon.com/resources/articles/2011/af_microadjustment_article.shtml
Each AFMA unit corresponds to 1/8 of the depth of field for a given lens at its widest aperture. So the +/-20 AFMA steps corresponds to 5X DOF.
For example, an image shot at 10 ft with a 100mm F2.8 macro lens will have a DOF of 0.51' (range 9.75' to 10.26'). So 1 AFMA unit corresponds to a focus accuracy of 0.765"! I doubt most people's eyes are that accurate. Modern autofocus systems are quite accurate, as long as you correctly position the focus point where you want it. I suspect a lot of the grumbling on this board about focus accuracy can be traced to poor technique.
Before you fire up the flame throwers, go check Roger Cicala's blog on LensRentals.com.
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