How accurate should one expect autofocus to be?

Started Mar 30, 2013 | Questions thread
Teleboy
Regular MemberPosts: 128
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Re: How accurate should one expect autofocus to be?
In reply to Teleboy, Mar 30, 2013

Teleboy wrote:

Can I just throw my hat into the ring and share some recent experiences on precisely this front - both with my D4 and D800. Good focus at short(ish) distances with telephoto lenses and moving or swaying subjects really demands that you stop down from 2.8; and not only that, but base iso is probably not recommended either. You should, I suggest, increase the sensor's sensitivity to better stop action. I think we often forget this important piece of information: shutter speed is not enough by itself. So much so that I would probably recommend you keep an ISO of 400 or higher running permanently in such situations, with the lens stopped down to 3.5/4/5/5.6 and as high a shutter speed as possible.

....Do that and I believe you (and a lot of people on this forum - some or many of whom, like myself, have only recently started playing with FX) will suddenly find you're getting a hit rate of 80-90% or more (depending on other aspects of technique) - and by that I mean TACK sharp focus: not an approximation of focus achieved by expanding DOF.

Anyway: that's my twopence, after running an experiment over the past couple of days at a wedding I am shooting at (and am still attending here in Austria!).

T.

I'm doing this with my 24-70 2.8 too (not only my telephoto lenses), and finding it really helps.

A.

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