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06-20-2019, 07:42 AM   #1
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SDM lens failures

Hi all I see some Pentax lens have SDM failures is there any lens that do it more than other ? is it just Pentax or do Sigma / Tameron do it as well?
I haven't a lens that isn't screw drive ( yet)
I know some one here was repairing SDM lens to screw drive ( I cant remember there name )
Thanks

06-20-2019, 07:45 AM - 2 Likes   #2
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QuoteOriginally posted by robert52 Quote
Hi all I see some Pentax lens have SDM failures is there any lens that do it more than other ? is it just Pentax or do Sigma / Tameron do it as well?
I haven't a lens that isn't screw drive ( yet)
I know some one here was repairing SDM lens to screw drive ( I cant remember there name )
Thanks
All in-lens motors can fail. Screwdrive can also fail.

However, the only SDM lenses particularly prone to failure were the original DA*'s launched around 2008 (such as the 16-50mm, 50-135mm, and 60-250mm). Lenses launched since then use different motor types (see the article below) and have proven far more reliable. Pentax also introduced a fix several years ago which has improved the reliability of new production runs of the aforementioned lenses.

The 5 Lens Autofocus Drive Types Explained - Articles and Tips | PentaxForums.com

So, TLDR, there's no reason not to get an SDM/DC lens these days, and plenty of reasons to get one IMO

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06-20-2019, 07:48 AM   #3
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Thanks for that 1 lens I was looking at 50 /135 lens 2nd hand
06-20-2019, 09:00 AM - 2 Likes   #4
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QuoteOriginally posted by robert52 Quote
Thanks for that 1 lens I was looking at 50 /135 lens 2nd hand
This is a great lens by all means and is Screw Driver convertible. Besides.. the SDM failures albiet true can come back to life once heavily used. I have about 3 DA*s that show the wake up issue. Once up they work very well. It seems the tolerances with these SDM motors was so tight that any over torqued assembly of these motors on the lens ended up having trouble with failure like symptoms (atleast that is my observation).
I have seen comments on the forum around the motor mount screw being too stiff and once wriggled gives motor a chance to rotate bringing back that seemingly dead SDM to life. I have not tried that myself.. but the more I use the SDM the more it seems to be freeing up. I have one 50-135 that came back to life when I used that on my K-01 that refused to wake up. I made it focus on a wall that did not have much contrast in it making the focus motor run end to end seeking focus. It did heat up quiet a bit when I did that (out of frustration..) but it came back to life again. I was almost going to burn it out but the battery depleted just in time so I guess it survived the abuse.
These motors also show some temperature sensitivity (as in very hard to get them out of slumber in winter vs in summer). Once woken up they behave normally. The screw drive conversion of course bypasses this SDM and brings back the lens to life with no problems whatsoever (except the noisy gear drive).

06-23-2019, 11:30 AM - 1 Like   #5
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QuoteOriginally posted by robert52 Quote
Hi all I see some Pentax lens have SDM failures is there any lens that do it more than other ? is it just Pentax or do Sigma / Tameron do it as well?
I haven't a lens that isn't screw drive ( yet)
I know some one here was repairing SDM lens to screw drive ( I cant remember there name )
Thanks
I have a DA200 that the SDM failed. UncleVana here on this forum fixed it for me. He is fantastic to work with. The screw drive works great, and I'm very happy with the lens, now.
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