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01-18-2021, 09:31 PM   #1
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SDM failure

I bought four * lenses in 2014. So far, my 55 and 300 motors have failed completely, my 200 is in an advanced terminal stage, only the 60-250 is still performing. To me it seems unwise to repurchase, or even to recommend the purchase of these products.

Is there any reason to suspect, other than anecdotally, that changes have been adopted in the manufacture of these first gen SDM lenses that would allay one's fears?

01-18-2021, 09:37 PM - 1 Like   #2
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QuoteOriginally posted by Nakedgun Quote
I bought four * lenses in 2014. So far, my 55 and 300 motors have failed completely, my 200 is in an advanced terminal stage, only the 60-250 is still performing. To me it seems unwise to repurchase, or even to recommend the purchase of these products.

Is there any reason to suspect, other than anecdotally, that changes have been adopted in the manufacture of these first gen SDM lenses that would allay one's fears?
Ugh, sorry to read this.

The good news is that the 55, 200, and 300 can all be converted to use screwdrive.

I don't believe there is any official word that more recent copies of those lenses have more reliable SDM motors.
01-18-2021, 09:39 PM   #3
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Converting to screwdrive is something I wouldn't mind, but the process is quite beyond my understanding, from what I have read about it.
01-18-2021, 09:47 PM - 2 Likes   #4
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QuoteOriginally posted by Nakedgun Quote
Converting to screwdrive is something I wouldn't mind, but the process is quite beyond my understanding, from what I have read about it.
Mine, too, however we have a Hulk @UncleVanya: SDM to Screwdrive Conversions - PentaxForums.com

01-19-2021, 05:36 AM   #5
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Here is the status of the four SDM lenses I own:
  • 16-50mm f2.8 converted to screw drive
  • 55mm f1.4 SDM motor failed and replaced in 2020
  • 50-135mm f2.8 intermittent fault where it freezes up
  • 300mm f4 works fine
If the option had been available to convert the 55mm to screw drive I would have done that, however the 55mm (like the 17-70mm) is KAF3 which means it is not possible to focus it with the camera screw drive. The others are KAF2 so can be converted. According to the previous owner (a member of this forum) the 16-50mm focused faster with the screw drive than it did when the SDM motor worked. I love the image quality of these lenses and have taken some great photos with them, but the reliability of the focus units is a problem. I have seen accounts on various forums that the newer batch of motors which replace non-functioning units in recent years have significantly improved reliability. So far my 55mm with a new SDM is working very well.
01-19-2021, 06:34 AM   #6
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Our local Pentax repair place won't do the screw drive conversion - says it's not adviseable. Makes you wonder who the customer is, the person who has the lens or the company.
01-19-2021, 07:24 AM - 1 Like   #7
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QuoteOriginally posted by luftfluss Quote
Ugh, sorry to read this.

The good news is that the 55, 200, and 300 can all be converted to use screwdrive.

I don't believe there is any official word that more recent copies of those lenses have more reliable SDM motors.
The 55 cant be converted sadly.

The sdm lenses I own/status:
Da* 16-50 bought w/dead sdm, converted to screw drive

Da* 50-135 bought w/supposedly dead sdm from what looked like the closing inventory from Pentax USA Colorado office. Lens was pristine. Manipulated sdm manually, it woke up, has never given any issue since. (5+ years?) I suspect it was an sdm replacement lens.

Da* 55 - bought used, no problems ever.

Da 17-70 bought refurbished, eventually gifted to my niece about 4 years ago. It is her primary lens, still going strong.

Da* 60-250 bought used from Pentax rep 5+ years ago... Still works great.

Da* 200 purchased used from Pentax rep 5+ years ago. No problems to date.

Ive no idea why some people have horrible luck with sdm. Ive had great luck, but the lack of luck for others is why I offer the conversion service. I hate to see these lovely lenses sitting around unused. Only the 16-50 / 50-135 / 200 / and 300 DA* lenses can be converted, but those are such loved lenses that I feel good about doing it.

01-19-2021, 08:07 AM   #8
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Thanks for the correction.

My only SDM lens is the 17-70, bought used, and it is doing fine.
01-19-2021, 09:58 AM   #9
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QuoteOriginally posted by Nakedgun Quote
Is there any reason to suspect, other than anecdotally, that changes have been adopted in the manufacture of these first gen SDM lenses that would allay one's fears?
There was a report at one point from a quote of a Pentax rep at one of the photo shows that vaguely indicated new build lenses had a change that 'fixed' the issue. It has been years but I'm sure it is still on the forum someplace. The biggest indicator that something changed is that the number of SDM lens failures is greatly reduced from what it was. That indicates to me that older lenses that were going to fail have failed and newer lenses have less of a chance of failing Not no chance, just a more 'normal' failure rate that is in line with industry norms. I suppose @UncleVanya would have a better sense of what the trend is and whether it is new or older lenses that are failing than I would. My impression is just from reading the topics on this forum and observing the change over the years.

My 16-50 motor failed and it was converted to screw drive
My 60-250 motor failed and I had the motor replaced at a repair shop and then sold it on.

I am considering buying a new 60-250 but since most of my work is now FF I hesitate. Not because of the motor as I do think new ones would have an acceptable failure rate but because I cannot decide between 60-250 and 70-210.
01-19-2021, 11:11 AM   #10
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I noticed some weak correlation between my SDM lenses' packaging and how they're performing:

DA*300 - bought in late 2016, focuses fine even after being unused for long periods - came in new gray "Ricoh" box
DA*55 - bought in early 2017, now needs to be "woken up" by turning the focus ring by hand if not used for a day or so - came in old black "Pentax" box
DA*60-250 - bought in mid 2017, focuses fine but squeaks when it focuses - came in old Pentax box
DA*50-135 - bought in late 2019, focuses fine - came in new gray "Ricoh" box

The focusing noise of the DA*300 and DA*50-135 is distinctly different and more closely resembles DC lenses such as the 20-40. I also find the 50-135 and 300 to focus pretty quickly contrary to most people's experience. Not DFA*50 fast but quite acceptable.
01-19-2021, 12:37 PM   #11
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I only have two SDM lenses, the 55 & 50-135, and neither has had any problems. The DA55 was purchased in May 2018 from B&H, SN# 9135457. And the 50-135 was purchased from off of eBay, June 2019, SN# 9305678. They both have sometimes gone over a month without being used, but focus without any hesitation. When I was looking for the 50-135 I paid attention to ones with the latest SN I could find.
01-19-2021, 12:46 PM   #12
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I have the DA*60-250, DA*200, and DA*55 1.4. The 200 can be a little sleepy at times but always comes around. The others work great. MY 60-250 is close to 10 years old, and has been used for thousands of images. It owes me nothing.
01-19-2021, 01:33 PM   #13
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QuoteOriginally posted by UncleVanya Quote
Da* 50-135 bought w/supposedly dead sdm from what looked like the closing inventory from Pentax USA Colorado office. Lens was pristine. Manipulated sdm manually, it woke up, has never given any issue since.

Forgive me if we've discussed this before, but what was your magic procedure for waking up the SDM on this lens? I'd like to have another go at waking up my 60-250. Serial number is 9229636. I've tried one procedure I ran across somewhere, but no luck.
01-19-2021, 02:06 PM   #14
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QuoteOriginally posted by jatrax Quote

I am considering buying a new 60-250 but since most of my work is now FF I hesitate. Not because of the motor as I do think new ones would have an acceptable failure rate but because I cannot decide between 60-250 and 70-210.
The 60-250 is very easy converted to FF. I have done it recently, and it is perfect at FF, really no dark corners visible as you can see in the topic about the conversion of my 60-250.

3D part for Pentax 60-250 zoom? - Page 2 - PentaxForums.com
01-19-2021, 02:42 PM   #15
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QuoteOriginally posted by Apet-Sure Quote
Forgive me if we've discussed this before, but what was your magic procedure for waking up the SDM on this lens? I'd like to have another go at waking up my 60-250. Serial number is 9229636. I've tried one procedure I ran across somewhere, but no luck.
I don't recommend it as I had one person tell me they had a lens band inside the lens break doing this but at your own risk as they say.

First power on and try AF. It won't work.
Second Set the camera and lens in manual focus mode.
Next grab both and forcibly turn them in opposite directions quickly back and forth exercising the manual focus/autofocus clutch part of the lens. I didn't invent this - but I can't find the origin of it. It seems hard to explain but essentially you are tying to turn the focusing collar very rapidly and a bunch of times. I did mine for almost 5 mins before I tried it in Autofocus mode again.

There is a variation on this where you use a screwdriver on the pawl (?) that is on the lens at lower speed than I describe.
Another variation requires partial disassembly for more direct access to the SDM motor and uses a screwdriver to turn it - I think.

Superstition says giving it time on the mount of a camera is needed due to "capacitors" needing to be charged. But I don't subscribe to this view. In my case I had tried a few times of a few minutes at a time with the lens on the mount in AF mode for "trickle charge" but without any change.

I tried the grab and twist and it worked - never to fail again so far. My theory is that it was an SDM repair/replace and it had sat long enough to get stuck or had some residual friction that needed to be ironed out.
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