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12-30-2008, 08:00 PM   #16
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QuoteOriginally posted by hwblanks Quote
This is an interesting thread, as I've thought about exchanging the 16-45 for the DA17-70 for the SDM capability, along with the increased zoom range. Now I'm beginning to question the wisdom of doing that, as faster focusing is more important to me than quiet focusing.

Heather
Ditto...

Remind me what the point of SDM is if not speed? Silence and marketing?

12-30-2008, 08:36 PM   #17
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I think that's what upsets people.
12-30-2008, 08:50 PM   #18
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Interesting. I have no complaints about the SDM on my DA*300mm. OTOH, the concerns I'm reading here are similar to mine with my Sigma 70-200mm HSM.
12-30-2008, 09:29 PM   #19
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QuoteOriginally posted by dadipentak Quote
concerns I'm reading here are similar to mine with my Sigma 70-200mm HSM.
You're saying this is slow for you?
Another poster mentioned on DPR that it's the first lens that seems to work w/ AF-C...

12-30-2008, 10:42 PM   #20
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Well I played with the DA 17-70mm f/4 SDM at my local Pentax agent last week and focusing is definitely much better when compared to the DA 16-45mm f/4. Given the choice I would opt for the DA 17-70mm. The focus throw is shorter and altogether quicker.
12-31-2008, 06:20 AM   #21
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QuoteOriginally posted by kenyee Quote
You're saying this is slow for you?
Another poster mentioned on DPR that it's the first lens that seems to work w/ AF-C...
Not slow exactly: more like indecisive & inconsistent.
01-02-2009, 07:23 AM   #22
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I like that SDM is quiet but a boost in speed would be SO much appreciated.
01-02-2009, 07:41 AM   #23
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QuoteOriginally posted by Marcus Quote
I like the 50-135 a lot but the SDM is not on the top of the list as to why. The AF is good enough at most times. But on the K10D, the AF can be a little antsy at times. Perhaps it's due to the longer focus throw.

I'd like to test the 50-135 up against the Sigma 50-150 to see which has the shorter focus throw. I think it would be interesting.
You guys could be right. I came back from a hot camping trip the other day and the 50-135 was nailing focus. Very assured and accurate. Something it wasnt doing in the first week of obtaining it. Took some amazingly good photos where I wouldve thought AF would be a problem.

Overall I dont mind SDM in the 16-50 and 50-135, i like the silentness of it. It might be in my head, but I think they are both noticably quicker in AF than the 18-55 II kit lens. Quick enough for what I do anyway. The 16-50 especially seems to focus as accurately and assuredly as I'd like so I have no complaints.

01-02-2009, 08:10 AM   #24
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QuoteOriginally posted by gawan Quote
I have only one SDM lens - DA* 16-50mm. It has provide me great images, and seem often very versatile, but still I often don't quite trust the capabilities of the ultra sonic autofocus of the SDM motor. It sometimes works very well, but sometimes it just does not get the focus, or lock, regardless of lighting situation.

My screw focus lenses never fail to works unless it is very dark and no contrast is to be found.

What are your experiences with SDM?
Allow me to link to a thread I started in February: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/21436-af-wont-...asionally.html

After I got the lens + body back from Pentax, another problem occurred: https://www.pentaxforums.com/forums/pentax-dslr-discussion/30855-not-very-hap...m-germany.html

When I got everything back the second time, all seemed solved but within two weeks another - not at all related - problem occurred in the body. The body is still in service right now. So, I can't say for sure if the original problems were definitively solved.
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