PIX 2015

Brilliant lesson in realities of AF - Roger Cicala's article

Started Aug 2, 2012 | Discussions thread
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Regular MemberPosts: 154
Re: Indeed.
In reply to BJN, Aug 2, 2012

I hope you don't mind my dropping by, but I just wanted to say "thank you". For the compliment and for the very enjoyable and rational discussion which I appreciated. It's nice to read comments from people who understand what I'm trying to do. Crudely still, but trying.

I completely agree with the single camera comments regarding the last post in the series. In the earlier ones we did use multiple lens samples (although I only graphed one example for each lens type). The last test did use a single camera for time reasons: when we set up Imatest at a given focal length and camera, we can test multiple lenses without recalibrating the setup. The last test, using different cameras, requires a recalibration each time we change bodies, about a 45 minute process. In compromise I checked each body we used outside the test to make sure it was working perfectly (and picked copies that were less than a month old) before mounting and calibrating them.

It isn't the best way and I would have liked to test at least 4 copies of each body. I did repeat the 7D tests just because I was so surprised at how badly it did and the second body was just like the first.

I really hope someone else, maybe Lenstip or DPR, will repeat some of these tests. Until another person in another lab finds the same thing I won't be absolutely comfortable with the results.

Roger Cicala

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