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02-24-2009, 07:28 AM   #1
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AF Speed x Body

Anyone with technical experience in this subject?

I basically want to know how much AF speed (SDM x Screw type) depends on the camera body.

And let me propose another question too: is it possible that the current Pentax SDM lenses will perform better with the new bodies to come? Not better like K10D x K20D but much faster, at least like K2000.

For instance, any chances that the new DA* 55 f/1.4 will have a better SDM performance in a new body or the AF speed is set in the design of the SDM and limited by it?

Thanks for any clarifications on the issue.

02-24-2009, 10:38 PM   #2
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I think it's an interesting question so I'm going to take a guess at it. The body can affect AF speed in one way, by a better AF technique. So that's separate from the drive system. There are big speed differences in the various screw drive cameras, even between the *ist D and *ist DS models. So the screw drive system isn't stuck at one design speed.

But I'm not sure about the SDM system. If you buy a lens today, it still has the same motor five years from now. You'll see some improvement from AF technique, but I don't know if the motor can go faster, or by how much. Pentax often designs with the future in mind, so I think the potential is there. However, I think this particular lens was not designed with AF speed in mind. They may not want it to go faster.

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