Gear Talk > EOS Bodies - For Stills
How does Mk. III handle 2 micro AF adjustments?
markko:
--- Quote from: neuroanatomist on May 01, 2012, 02:42:43 PM ---Thanks! How finely? For example, what do 85mm and 200mm look like on the 28-300mm?
--- End quote ---
I don't have a 28-300m, but I did some tests with my 70-200mm II and 100-400mm:
neuroanatomist:
--- Quote from: markko on May 01, 2012, 04:14:58 PM ---I don't have a 28-300m, but I did some tests with my 70-200mm II and 100-400mm:
--- End quote ---
Wonderful, thanks!
Z:
Thank you very much markko, I think that answers our question!
markko:
--- Quote from: Z on May 01, 2012, 05:07:02 PM ---Thank you very much markko, I think that answers our question!
--- End quote ---
Welcome :)
One question remains unanswered, though: how do you pick the right value for adjustment!? :-\
I have the Lens Align tool, but still: I just used it by night in the living room and the difference in the values is so little... I think I have to use it at daylight, so that I'm really really really sure that I see the red dot through the center hole (and the lens is aligned properly with the tool).
The odd thing happened that the tool suggested an adjustment that I would expect the opposite when I was looking at real world pictures.
neuroanatomist:
--- Quote from: markko on May 01, 2012, 05:54:38 PM ---One question remains unanswered, though: how do you pick the right value for adjustment!?
--- End quote ---
No simple answer there. In selecting a single AFMA (for my 5DII and 7D), I consider both the results at the different distances in terms of DoF for a given focal length, and also the distances which I commonly shoot for those lenses. I test at two distances - 25x and 50x the focal length, and for zoom lenses I test at both ends, and multiple intermediate points. For example, the value I chose for the 35L is biased toward the closer distance, since that's where DoF will be thinner; I picked the value for the 85L based on the fact that I usually shoot that lens at about 7-8 feet for portraits, which is ~25x the focal length. For lenses like the 70-200 II, which I shoot at varying focal lengths and distances, I selected values biased toward the long end of the zoom range, since that's where DoF will generally be thinnest and focus most critical. Selecting adjustments for the 1D X will be similar - weighting the choices for both ends based on what the values in the middle are, where I shoot the lens most, and where DoF will be thinnest.
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