[FozzFoster]

Hi all,

I have an opportunity to buy a used 50-135mm with what appears to be the classic SDM failure.
The price is only $350 CAD (usually sells for $1300 CAD new).
This lens wasn't really on my radar as 'need to have' but at that price....
Still not sure if I want it, I am saving for the new flagship and hopefully the 16-50 PLM when it comes out.

However...

I've looked up videos on how to replace the lens profile in debug mode, however a few commenters in the video say they were unsuccessful compiling with newer cameras such as the K-3 II. I saw no comments on peoples experience compiling using an even newer camera, the K-70 which I own.

Can anyone vouch for completing the process with a K-70 and 50-135mm and which steps/programs did you use (could you please provide a link?)

Thanks in advance!

[jatrax]

I think @UncleVanya is the local expert. He will (or did) do the conversion for you if you do not want to it yourself. I did it on my 16-50 but I think I used the k-x to do it at the time.

[Kozlok]

I don't think the K70 works. Sadly.

[c.a.m]

50-135mm with SDM failure, worth the buy?

If the lens is in excellent shape otherwise, that is a great price. It's a wonderful lens.

I have one that I converted to screwdrive using my K-5 II. The procedure is relatively easy, assuming that one is comfortable following explicit step-by-step instructions and editing text files. However, there is a risk that a mistake could be made that could cause problems.

Other than having someone do the conversion for you, acquiring a cheap Pentax camera might be viable, albeit at increasing your overall cost. I think that cameras up to and including the K-5 II/s will work, but you should confirm that in the applicable threads in PF.

Edit: I believe this was the main post that I used for instructions: https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/208353-how...ml#post3083922

I don't know if that post is still one of the primary references for the conversion. I also recall that there were a couple of Youtube videos.

- Craig

---

Last edited by c.a.m; 03-18-2021 at 12:47 PM.

[mbceft]

Here’s the post with he video. How To: Convert SDM to ScrewDrive + Video - PentaxForums.com
I used it this last weekend to convert my 50-135 with my K5ii

I just check the support files and K-70 doesn’t have a debug file folder in the Dropbox link but there is a link in the post to the PF member that offers the service.

[Marc D.]

I have the same opportunity (350 €) but I worry about
1 : this problem (SDM fail)
and
2 the fix with screw drive

Is the fix the same for all SLR or is it different for each one ?
Is it always OK respecting the instructions or may be even with good instruction a rik of malfunction ?

350 € is few for a pentax but if the AF doesn't work it is 350 € lost. I can buy a manual focus.

[i_trax]

I dedicated my faithful K10D for this exact purpose.
The firmware is 1.20 and ready for failed SDM lenses.
Fortunately all my SDM lenses are still working OK although 300 and 60-250 start getting occasionally a bit slow.
I heard that the trick is to use them regularly , unfortunately with my full titanium left arm replacement and both hands attacked by the Dupuytren contracture it was rather not possible.
Just had my right hand operated so the situation must improve.

[blackcloudbrew]

I had @UncleVanya here convert my DA*16-50 and 50-135, both of which were working with sleepy SDM. He did a great job, at a very reasonable price and very workable turnaround time. I did it to just get over the SDM issue. Prior to getting my K-1 those two lenses formed a great couple of lenses for lots of things. Now with the screw drive only, they are zippy at focusing. I agree with c.a.m above that if the lens is in good shape optically, get it and just convert it yourself or by @UncleVanya.

[FozzFoster]

acquiring a cheap Pentax camera might be viable

I dedicated my faithful K10D for this exact purpose.

I guess I could relegate my K-5 to strict 50-135 purposes... I had planned to sell the K-5 once the flagship came out and have my K-70 as backup.

hmmm all in I don't really think it's worth it, I'm already squeezed for cash and would prefer to use the lens on newer cameras.

[c.a.m]

I'm already squeezed for cash and would prefer to use the lens on newer cameras.

Well, your kit includes a number of excellent lenses already, so not a big miss if you pass on the 50-135. I don't have any exceptional prime lenses in the 50-135mm range, so I use the DA* 50-135 instead.

- Craig

[dbs]

Hi Fozz

The older camera is for the debug mode to convert the SDM to screwdrive.

[ramseybuckeye]

Hi all,

I have an opportunity to buy a used 50-135mm with what appears to be the classic SDM failure.
The price is only $350 CAD (usually sells for $1300 CAD new).
This lens wasn't really on my radar as 'need to have' but at that price....
Still not sure if I want it, I am saving for the new flagship and hopefully the 16-50 PLM when it comes out.

However...

I've looked up videos on how to replace the lens profile in debug mode, however a few commenters in the video say they were unsuccessful compiling with newer cameras such as the K-3 II. I saw no comments on peoples experience compiling using an even newer camera, the K-70 which I own.

Can anyone vouch for completing the process with a K-70 and 50-135mm and which steps/programs did you use (could you please provide a link?)

Thanks in advance!

If you want the lens and are willing to pay for the conversion (or buy an old camera to do it) I would think it's a no brainer.

[UncleVanya]

I have the same opportunity (350 €) but I worry about
1 : this problem (SDM fail)
and
2 the fix with screw drive

Is the fix the same for all SLR or is it different for each one ?
Is it always OK respecting the instructions or may be even with good instruction a rik of malfunction ?

350 € is few for a pentax but if the AF doesn't work it is 350 € lost. I can buy a manual focus.

The lens is what is reprogrammed. All Pentax DSLR bodies have engaged screw drive fine on all lenses I have converted. Remember people only send me a lens the conversion - I convert and test on my cameras. They use on theirs. Most send me a lens because they don’t have older bodies to use. The conversion is permanent (reversible) and so far it works with all compatible bodies including the k-1. The issue with newer bodies is that Pentax seems to have removed the code in those bodies that allowed people to reprogram lenses.

[brianmquinn]

I bought a used 16-50mm and a 50-135mm off of ebay for cheap as they had SDM failure. They were each about $200 with shipping. I converted them both with my K5 and they worked great after that. There was one issue with the 16-50mm however. When using the viewfinder autofocus I found that while the lens would auto-focus it was often off by a bit but sometimes it had perfect focus. If I used the live view auto-focus it was perfect every time.

[i_trax]

just to clarify
the K10D ( with firmware 1.20 ) will ignore SDM , will use screw driven AF only ,so the lenses do not need to be modified / altered .