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| p.1 #4 · FoCal's test results on 6D AF consistency |
One thing to note, though: different lenses have different AF accuracy within a system. There are many other factors involved, but for simplicity:
1) Camera tells lens to go here.
2) Lens goes here, camera rechecks
3) If needed repeat
Let's say camera A can be accurate to +/- 0.5 and camera B to +/- 0.1.
If the lens is accurate to + / - 0.5, changing cameras may make no difference even though B is better.
This is fairly true. For example the Canon 50mm f/1.4 can recognize about 750 steps of command, while the 85 f/1.2 can recognize over 4,000 steps. Plus steps are not linear throughout the focus range. A macro like he tested with Canon has fewer steps at infinity and more at the macro focusing range. I'd be very hesitant to compare between brands unless very similar lenses were used, and even then only with great care.
One other thing to note: contrast detection AF is much more light and ISO dependent than phase detection. If you shoot at ISO 3200 phase may be just as accurate as at 400, but contrast is not.
I agree the results are very interesting. But having done some of these type tests myself, I found there's an awful lot of variables and extrapolating too much is a temptation.
Edited on Dec 18, 2012 at 06:22 PM · View previous versions