Well, the DA* 50-135mm SDM is probably the slowest AF lens on Earth, gaining
it the nickname of "the sloth". Generally speaking, SDM lenses are slower
than both screw-driven ad DC Pentax AF lenses, so the DA 17-70mm is a good
candidate for being another slow-AF lens. However, I own it and I don't find
it THAT slow as you pointed out.
There is however another problem I saw on several samples of that lens and
is the almost impossibility to autofocus above 50mm focal length, hunting
forever while you try & find the focus. Perhaps that's the problem you
spotted.
Dario
-----Messaggio originale-----
From: David J Brooks
Sent: Wednesday, March 19, 2014 11:17 PM
To: Pentax Discuss
Subject: Pentax 17-70 f4 and SDM motor question
Hi all
I went to pick up above mentioned lens this afternoon. loks and feel
nice on the K-5, however me thinks there is a problem.
I know the AF of Canon and Nikon are quite fast leaving us Pentaxians
hunting and pecking our way through landscapes and soccer photos, BUT,
2-3 seconds to lock on and focus on a static object.?? Me thinks
that's a bit to slow.
The salesman and i played with it for 10-15 minutes. It did get a tad
faster to focus but it was still painfully slow. I know it will not be
as snappy as my Nikon 70-200 f2,9 VR lens, you can barely hear
anything and it locks on faster than Mike Johnson deleting a cat
photo.
So, am i missing something with this SDM system. Is it painfully slow
or should it be as fast or faster to AF on a subject as the screw
focus lenses. Do i need to adjust a menu setting or something.
Another is on order for Saturday
Dave
--
Documenting Life in Rural Ontario.
www.caughtinmotion.com
http://brooksinthecountry.blogspot.com/
York Region, Ontario, Canada
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