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 Robin Casady, Mar 31, 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.

Just for clarification, are you saying shoot at f/4 or smaller, and raise ISO so you can get a faster shutter speed at that f/stop?

When you say, "...shutter speed is not enough by itself." do you mean that you need a smaller f/stop with the shutter speed? Or, are you saying that raising ISO, by itself, has some effect on getting sharp images?

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Robin Casady
http://www.robincasady.com/Photo/index.html
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."
— Bertrand Russell

Hi Robyn,
Sorry for the delayed response: I'm travelling and writing to you from Dusseldorf Airport! Basically, yes: 3.5 or higher and yes, higher ISO itself helps freeze action and thereby sharpen shots to the extent the camera is able to control noise. But judging by your galleries, I don't think you needed me to tell you that lol! :). From what I can see on my iPhone, seems like you have some nice product.
T.

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