[krazny]

I recently bought a used 60-250 lens of Ebay.

The lens was listed as being manual focus only (SDM failure I assumed).

I was aware that I could convert it to screwdrive focusing and that I needed an older camera model to perform the conversion.

Luckily for me I have a K-5 which is suitable for the converson.

When the lens arrived I put it on the K-5 and ... nothing. The lens didn't focus, as expected.


I then followed the true and tried instructions found here: How To: Convert SDM to ScrewDrive + Video - PentaxForums.com

I was lucky enough that the conversion worked in first try. After I had uploaded the edited lens file and deactivated the debug mode I switched the K-5 off and then on again and heard that beautiful sound which is the screwdrive!

Success! I am a master hacker! Focused on few things. Success confirmed.


I then removed the lens of K-5 and attached it to my KP believing I had converted it successfully. I had not attached it to the KP before I did the screwdrive conversion (may be important).

Oddly enough the lens makes no noise but it DOES FOCUS. SDM revived?

I tried it again on the K-5. At first try, nothing happened. I switched it back to the KP and it still focuses on the KP. I again attached it to the K-5 and oddly enough if I hold the focus button for a couple of seconds the lens starts to focus, silently, Screwdrive off and the SDM lives.


Since I didn't try it beforehand on the KP I don't really know what the success is. The lens definitely did focus with the screwdrive on the K-5 but then went silent focusing on the KP.

Anyone have any idea how this managed to happen? I'd love some insights.

cheers

[clickclick]

No clue, but interesting. My 16-50 has hit the point it needs to be woken up if I don't use it regularly. I'd love to be able to have it work as it did when new. Wish I had a compatible camera to play with the conversion.

[jatrax]

That is interesting. I wonder if @unclevanya would have seen that behavior.

[Rondec]

Odd. My understanding was that the DA *60-250 couldn't be converted even though it does have the dual screw drive/SDM auto focus. The 16-50/50-135/200/300 will convert, but not that one.

[UncleVanya]

Odd. My understanding was that the DA *60-250 couldn't be converted even though it does have the dual screw drive/SDM auto focus. The 16-50/50-135/200/300 will convert, but not that one.

The normal behavior is that it seems to randomly go back and forth fighting between screw drive and sdm. If sdm is completely dead this generally means a jerky intermittent screwdrive focus and gaps of random length of no focusing. Given how exercising a lens with screwdrive can sometimes wake up sdm that has frozen that could happen I suppose. The normal conversion is highly unreliable on a 60-250 so I have no clue why this is working.

---------- Post added 07-02-21 at 10:20 PM ----------

I then followed the true and tried instructions found here: How To: Convert SDM to ScrewDrive + Video - PentaxForums.com

I was lucky enough that the conversion worked in first try. After I had uploaded the edited lens file and deactivated the debug mode I switched the K-5 off and then on again and heard that beautiful sound which is the screwdrive!

Success! I am a master hacker! Focused on few things. Success confirmed.


I then removed the lens of K-5 and attached it to my KP believing I had converted it successfully. I had not attached it to the KP before I did the screwdrive conversion (may be important).

Oddly enough the lens makes no noise but it DOES FOCUS. SDM revived?

I tried it again on the K-5. At first try, nothing happened. I switched it back to the KP and it still focuses on the KP. I again attached it to the K-5 and oddly enough if I hold the focus button for a couple of seconds the lens starts to focus, silently, Screwdrive off and the SDM lives.


Since I didn't try it beforehand on the KP I don't really know what the success is. The lens definitely did focus with the screwdrive on the K-5 but then went silent focusing on the KP.

Anyone have any idea how this managed to happen? I'd love some insights.

cheers

Can you pm me? If possible I would like before and after files from your lens. I want to verify that there not a minor change somewhere - which would be an exciting discovery if it was repeatable.

[DWS1]

Interesting, perhaps you've stumbled upon a way to convert this lens. Would be nice to see if this can be repeated on another 60-250mm.

[sbc]

Years ago. I tried with my 60-250 just for the fun of it. There was nothing wrong with its SDM. But no luck because the lens could not decide if it wants to be screw drive or SDM. I remembered hearing screw drive once and then silent after that.

[krazny]

I uploaded the lenseep.lns files to pastebin if anyone wants to take a look at them besides UncleVanya.

60-250_original - Pastebin.com - This is the original file pulled from the lens.

60-250_edited-from_lens - Pastebin.com - This is the edited and uploaded file which I pulled from the lens.

60-250_backup - Pastebin.com - This is the backup file which is put on the sd card when I pull the lens file.

There may be a plot twist here however.

When I woke up this morning and turned on the camera the lens did not focus right away. It took a minute or longer for the lens to start to focus.

I did play a little with the lens when it arrived and at no point did it focus. However if the lens needed waking up, it is possible that enough didn't pass for that to happen before the conversion.

[ramseybuckeye]

Can you pm me? If possible I would like before and after files from your lens. I want to verify that there not a minor change somewhere - which would be an exciting discovery if it was repeatable.

That would be cool, I could imagine that there are quite a few of these lenses laying around unused for quite awhile.

I've deleted what I'd written before because my solution to the problem was transitory at best. Tried to use the lens again today, but it's dead, no AF at all, and rotating the focus ring has no remedial effect. So I don't recommend the solution I attempted, though I have no reason to believe that it could cause any damage.

[UncleVanya]

I've got a 55mm APS-C lens that has SDM but cannot be converted to screwdrive. When it died about a year ago, I sent it to Precision and they fixed it under warranty (imagine my surprise when they approved that instead of telling me it was "probable impact damage"). Then, about a couple of months ago, it started acting up again, and finally crapped out entirely.
I'd read in a few posts by different people that jerking the focus ring around seems to revive the SDM function. I tried that, and it seemed to help, but wasn't a permanent fix. It occurred to me that the problem must simply be a matter of friction, since the symptoms always include a gritty feel to the focus ring. I figure that when it starts to get stiff due to lack of lubrication or whatever it is that causes the friction, the real problem is that the motor isn't strong enough to overcome that friction. Well, one way to overcome friction is with wear. So I got out my battery driven 3/8" drill and stuck a sanding cylinder on it (1" rubber cylinder mounted on an arbor with a matching miniature drum-sanding cylinder mounted on it). I started it up slowly and brought the sander into contact with the focus ring, then I made it spin for a minute or so. Changed the direction of the drill, and did it again. Now it works fine. Though there's probably debris of some kind from wearing in the focus element that way, it's not apparent and the lens is still the sharpest one I've got.

My DA* 50-135 was purchased with "Dead SDM" from what we think was the selloff from Pentax HQ in Denver. It was pristine but SDM didn't work. I used a method where you exercise the focus ring back and forth - I did it pretty rapidly while attached to the camera but with MF selected. After 2-3 mins - I stopped - and SDM worked and has never given me a problem since. My guess is that it was a replacement/refurbished lens that had not gotten used after the replacement and stiction set in. This does not seem to happen with brand new lenses - perhaps some wear is needed - and even after long periods of disuse it keeps on working correctly so I'm not sure if there was some friction that was worn away or not. I exercised that focus ring pretty vigorously... I don't recommend it as I have heard of other lenses where this method was tried and things broke. I was inexperience in this area at the time. Your method seems less risky - as the back and forth nature of the method I used was pretty aggressive.

[Apet-Sure]

I was reading this thread with great interest. The SDM on my 60-250 quit working shortly after I bought it used. (Otherwise it was pristine and I never regretted my purchase since the price was so great.) I really don't mind manual focus either. Over the months I tried a few times to get it going again with no luck. But, after reading the comments above, I took it out and, off the camera, rotated the focus ring clockwise by hand for about five minutes. Then I rotated it counter-clockwise for another five minutes. Put it on the camera and tried AF. Nothing. Five more minutes clockwise and five more minutes counterclockwise. Voila! It's now working again! I'll be sure to take it out for exercise regularly now. Thanks y'all!


Update:
After waiting 10 minutes or so with the camera off, then turning it on, PDAF didn't work. Switched to LiveView and it worked. Switched back to PDAF and it worked too. Hmmm.... Ongoing testing and evaluation needed. Test camera is a KP.

[clickclick]

I started it up slowly and brought the sander into contact with the focus ring, then I made it spin for a minute or so.

I just want to be sure I'm interpreting this correctly. You were just using this as a method to spin the ring quickly for a long period versus turning it by hand?

My 16-50, which I bought new and worked great for years, has developed the SDM issue. I've tried various combinations of turning the focus ring back and forth by hand, spinning the screw drive mechanism back and forth with a jeweler's screw driver, and also just racking the focus by hand from one extreme to another while half pressing the shutter release or hitting the AF button to have the camera attempt to focus while I'm manually focusing it. One of these combinations seems to always wake it up, and then it will stay happy as long as I use it regularly. Kinda like the lens is jealous and punishes me for using one of it's siblings.

[krazny]

So checking in for the second time.

I went outside last night to take some photos of the sunset and found that my success may have been less than ideal.

I found that the SDM was somewhat inconsistent last night and it was like I was charging a capacitor to get it to work and when inactive the capacitor would drain. That is the feeling at least.


I decided to do a little experiment this morning. I re-uploaded the original lens file back to the lens through the K-5.

What happened is that the lens started focusing in screw drive and then switched over to SDM and then sort of seemed to stop working.

I tried to hold the focus button to "charge the capacitor" but all it did was to drain the camera battery. I went through two other batteries and nothing happened except for the camera claiming that the batteries were empty. I'm not sure if the lens was doing something BAD or if all three batteries were just close to empty. The latter is probable since I don't use the K-5 much and it has just been sitting.

There was a slight "OH $H*T" moment when I was trying the third battery. I tried to switch Live View on and see if it would focus that way. It started to focus and then the screen died with a lot of tearing.
I removed the lens and attached another one. There was a little flickering when I turned the camera on again so I assumed I had possibly damaged the camera. However after removing the battery and letting the camera stand for a while there doesn't seem to be any issue with the camera.


I then,somewhat reluctantly, attached the lens to KP and turned it on. No obvious issues. Battery is fully charged and no screen flickering.

When the camera started focusing it was with the screw drive. However it quickly switched to the SDM. I then turned it off and on couple of times. The sdm focusing was consistent.

I then removed the lens from the camera and waited c.a. 30 minutes. I attached the lens and at first nothing, but within 30 seconds the SDM kicked into action. I go through few cycles of turning it on and off while testing the focus. SDM mostly but sometimes it starts in screw drive but quickly jumps over to SDM.

I again removed the lens from the camera and waited over ten minutes. Awe and behold. The lens just kicks into action within few seconds.


As has been pointed out in this thread it seems that the SDM can be helped/fixed by rotating the focus ring or the screw drive. I haven't rotated either to a great extent but maybe that has helped. It is possible that these lens file exercises have nothing to do with the motor waking up. Who knows.

If you intend to try this for yourself I should add a warning. You might end up with a paperweight (or two). Take backups of all the files you use.

I guess I'll report in next weekend to see how it actually fared.

[UncleVanya]

Thanks for the update. The behavior seems not too inconsistent with known results. Screwdrive conversion appears to not work as intended, but as an unexpected bonus your sdm woke back up. That could help some people. Time will tell.