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11-27-2010, 04:16 AM   #1
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Is this Pentax way of admitting SDM was a failure?

I noticed the new Pentax DA 18-135 F3.5-5.6ED AL [IF] DC WR lens sports a new focusing motor, called DC, which is supposedly an improvement on SDM. I hope it proves more reliable.

Is this Pentax admitting SDM was a failure?

I struggle to understand what possessed them to wait this long to address the appalling failure rate of the SDM lenses (though of course not officially, not in the open), and I fervently hope they bring out a successor to the DA* 16-50 and 50-135 lenses soon.

11-27-2010, 04:40 AM   #2
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Let's not be too hasty with the presumptions mate.
SDM to Pentax is no failure, but the DC motor is an overhauled improvement.
There may have been limitations to improving SDM as it was, and so needed a change of tack.
In any case, SDM was bound to be a problem given the electronics (vs the screwdrive's mechanics) that are more prone to kicking the bucket. Whether there are higher failure rates with SDM as opposed to HSM or USM, who really knows, but each have their failings, whereas screwdriven lenses don't.

So is Pentax admitting SDM was a flop - nope, they've been flat out denying that to date. And I'm not convinced it is myself (well maybe a little...), on the overall scheme of things, even though I know there are many stories of SDM motor failures.

Last edited by Ash; 11-27-2010 at 05:00 AM.
11-27-2010, 04:44 AM   #3
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It is clear that they will not admit this openly.
But it is clear that SDM was a failure.
It is very slow and the fault rate is too high.

I doubt that we will ever see another, new SDM lens.

Only time will tell, if the new motor is any better.
11-27-2010, 04:50 AM   #4
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Hard to beat finger-drive for reliability.

11-27-2010, 04:58 AM   #5
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QuoteOriginally posted by Mike Cash Quote
Hard to beat finger-drive for reliability.
Not being cynical are you Mike?
That's unlike you.

Well, maybe you're right, and the reason why Pentax made quick shift...
11-27-2010, 05:06 AM   #6
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response to sdm

hi pentaxians, i have the 55f1.4 & as usual to be rebuffed how much speed do most people need to take a snap. loved the k5 review read it while in penang just got back & read the 18-135 review delicious cant wait sorry i kn ow its the wrong place every time to post my sentiments but i am so exited waiting to get the money together for ak5 & a18-135 thanks ian
11-27-2010, 05:13 AM   #7
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This could be seen as an implicit admission of failure as it includes abadoning an acronym; if something is successfull and highly regarded (e.g. "SMC") the term for it tends to stick and marketing is about <term> having been improved, <new term> implies replacing something (where the techincal reality and what is implied in marketing lingo don't always meet ;-)
11-27-2010, 05:21 AM   #8
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re failure.

sorry my friend but pentax has never been a failure just slow on the uptake look back in pentax history the first metering camera ETC ETC ETC.

11-27-2010, 05:21 AM   #9
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I've read on the web (interview with Ned ... I think it was) that the DC is for the cheaper lenses and will not replace SDM.

I guess time will tell.
11-27-2010, 05:23 AM   #10
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QuoteOriginally posted by jolepp Quote
This could be seen as an implicit admission of failure as it includes abadoning an acronym; if something is successfull and highly regarded (e.g. "SMC") the term for it tends to stick and marketing is about <term> having been improved, <new term> implies replacing something (where the techincal reality and what is implied in marketing lingo don't always meet ;-)
Or it may just be that the new technology is nothing like the old one and would be inaccurate to include the old acronym.
11-27-2010, 05:32 AM   #11
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My understanding is the DC motor is not an "improved" SDM motor at all. It is if anything a cheaper version of SDM for lower end lenses. As to whether or not it is any more reliable, no one has any idea. The first DC lenses just hit the market last week -- a little soon to say it is any better than SDM.

By all accounts, it is no faster than SDM. The focus throw on the 18-135 is shorter and so it gets places faster, but that is true as well for the DA 17-70 which uses SDM technology and is a pretty fast focuser.
11-27-2010, 05:42 AM   #12
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QuoteOriginally posted by cameraboy Quote
look back in pentax history the first metering camera ETC ETC ETC.
Before Kodak did it in 1938?

QuoteOriginally posted by Ash Quote
Well, maybe you're right, and the reason why Pentax made quick shift...
If doing it with your fingers is quick shift.....then is allowing the camera to do it slow shift?
11-27-2010, 07:26 AM   #13
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QuoteOriginally posted by Rondec Quote
By all accounts, it is no faster than SDM. The focus throw on the 18-135 is shorter and so it gets places faster, but that is true as well for the DA 17-70 which uses SDM technology and is a pretty fast focuser.
From what I've heard this isn't true. The throw on the 18-135mm is apparently 120deg which is long enough for an autofocus lens.

Adam posted the review here and it looks good.
11-27-2010, 07:37 AM   #14
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QuoteOriginally posted by sterretje Quote
I've read on the web (interview with Ned ... I think it was) that the DC is for the cheaper lenses and will not replace SDM.
ditto...afaik, DC is cheaper than SDM. Wish they'd use real ring motors for SDM...even Sigma/Tamron have added ring motor technology
11-27-2010, 07:39 AM   #15
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If they're getting rid of SDM, I say good riddance. After reading every review I could find of the Pentax 50-135mm and the Sigma 50-150mm, I've decided to go with the Sigma.

The performance/reliability issues of the SDM was the deciding factor. The Sigma seems to have comparable image quality and focuses faster. And on top of that, it has a four year warranty compared to the ridiculous 1-year warranty of the Pentax. The skimpy warranty is just too much of a gamble for an $800 lens.
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