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05-26-2011, 07:09 AM   #1
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DA* 50-135 vs. DA* 16-50 SDM sound

Hi all,

I got the DA* 50-135 from a forum member two days ago and received my DA* 16-50 yesterday. I am quiet happy with the DA* 50-135 focusing until I received my DA* 16-50.

What I find out is the SDM in the 16-50 is much more quiet than the 50-135, there is little mechanical sound when focus all the way from one end to another, and there is virtually no mechanical sound in less extreme focusing.

The 50-135 however have much more mechanical sound than the 16-50. Do you think this is normal? I also feel that the focusing speed in the 16-50 is faster than the 50-135. Is my 50-135 starts getting SDM failure? or is it normal?

This is my first two SDM lenses so I have no experience w/ SDM lenese at all. Just comparing these two. Can someone with these two lenses give their opinion?


05-26-2011, 07:56 AM   #2
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The 50-135mm is a slow lens in focussing, so that could be your good feeling. Don't know about the other things.
05-26-2011, 08:07 AM   #3
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The DA*16-50 is virtually silent. No other SDM/HSM/USM lens that I own or have ever tested even comes close.

05-26-2011, 08:11 AM   #4
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QuoteOriginally posted by robgo2 Quote
The DA*16-50 is virtually silent. No other SDM/HSM/USM lens that I own or have ever tested even comes close.

Ditto to that. Every time I put it on the camera I think it's not working!

I've owned DA*16-50, 55, 50-135, and 60-250 and 16-50 is the quietest. None of the others were particularly loud, but definitely audible.

05-26-2011, 08:47 AM   #5
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Original Poster
Thanks for all the inputs. I feel much better now.

My experience:
50-135 focusing sound: a high pitch sound + little mechanical sound (like screw drive)
16-50 focusing sound: a high pitch sound + virtually no mechanical sound (like screw drive)
16-50 focusing is fast and very smooth (like damped well) compare to 50-135.

So this is normal...

What is/are the sign(s) of beginning of SDM failure then?

05-26-2011, 08:59 AM   #6
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QuoteOriginally posted by farfisa Quote
Ditto to that. Every time I put it on the camera I think it's not working!
I had the same feeling with the Sigma 150-500. With screw-drive lenses, I was used to waiting for the grinding to stop and the confirmation beep
05-26-2011, 12:25 PM   #7
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I just got my DA* 50-135 back from Pentax with a new SDM motor and was surprised like you that it still makes noise when focusing; kind of a squealing/whirring sound as it racks through the focus range. My other DA* star lens are virtually silent, DA* 200 is silent, DA* 60-250 some noise, and DA* 16-50 silent.
05-30-2011, 02:12 AM   #8

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My experience is also that the 16-50 is silent, but the 50-135 has some high-pitched 'squeaking' sound as it reverses (especially trimming in the focus close to lock) together with a barely-audible whirr as it moves through the range

05-30-2011, 10:43 PM   #9
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my take

I do not have either of them. But I do have da*55 and DA17-70. Both of them are using SDM motor. DA17-70 is a bit faster due to shorter throw. Both of them are not the quietest. There are slight high pitch noise at the beginning and at the end. DADA17-70 sounds like there a tiny bit sand somewhere in the end. But you have to hear it when very quite.

BTW, my DA17-70 bought from another member failed a couple of weeks after arrival. The symptom seems in the beginning to be non responsive from time to time. And it is only getting worse. Suddenly, it does not work any more. Fixed by Pentax and it works properly now. But it was not a pleasant experience to say the least.
05-30-2011, 10:49 PM   #10
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Some SDM motors squeak regardless of the lens. Start worrying when your lens becomes absolutely silent.
05-30-2011, 11:07 PM   #11
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One precursor to SDM failure I believe is the requirement for multiple pressing of the AF button before the SDM engages to autofocus the lens. This particularly happens at the beginning of a shoot after a lengthy break from use of the lens. One of those 'be aware but not alarmed' things...
05-31-2011, 09:35 PM   #12
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Yep, same symptoms with my latest copy of the DA*16-50 which I am sure is on its way out also. It was brand new but when I mounted it on my K20d, it took several pressings of AF before it s.l.o.w.l.y came to life. Then it squeaks while trying to focus, kicking and screaming albeit accurately.

Even now, after not using it for a day or so, it takes several tries to bring it back to life and the darn lens is less than two months old!

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