DotTune: Video Tutorial for AF tuning without photographs

Started Feb 18, 2013 | Discussions thread
Per Baekgaard
Contributing MemberPosts: 862Gear list
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Re: DotTune: Video Tutorial for AF tuning without photographs
In reply to Starred, Apr 1, 2013

Starred wrote:

Is it possible that there is significant difference in accuracy of the focuspoints at diffent focal lenghts?

Not sure if the accuracy as such changes, but the optimal micro focus adjustment may vary with distance (and zoom setting) for any given lens.

The "general" recommendation is often to adjust at 50x the length of your lens, so a 50mm should be tested at 50mm x 50 = 2500 mm = 2.5 m.

However, if you often use a particular lens at a certain distance, you may want to use that distance instead. This might be particular relevant for macro lenses, for instance.

For zoom lenses, the "general" recommendation might be to use the longest focal length as the basis for your adjustment, since the depth-of-field is smallest here and any errors are usually better tolerated at the shorter end of the zoom range.

Again, however, if you shoot more often at a particular range, you might want to use that range when you calibrate your lens.

Thus the "best" adjustment is typically a compromise, and you might have to find a balanced setting that averages over your most typical cases, in order to minimize the errors "on average".

Not much is perfect in this world

- Per.

 Per Baekgaard's gear list:Per Baekgaard's gear list
Nikon D70 Nikon D200 Nikon D300 Nikon D800 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR +14 more
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