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04-25-2015, 06:58 AM   #1
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DA* 50-135 Question

I think I know the answer, but before I send the lens to Precision for repair, I thought I would double check here. I had a lens repaired once by CRIS about 2 years ago. I am not sure if they changed the SDM motor at that time. Recently, the lens started having problems focusing -- slow to focus and having trouble locking focus -- I then noticed that when I turn the zoom ring, the focus indicator inside the window moves with it. I don't remember that ever happening before. My 60-250 zoom does not do that.

Can someone confirm that this is not normal behavior for this lens.

Also, anyone have recommendations for any place other than Precision and their automatic $305 charge?

Thanks in advance.

04-25-2015, 07:15 AM   #2
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I haven't noticed that with mine but it does sound like the SDM might be failing. I just sent my 16-50 to Precision and the upfront charge is $206. I've called around to different repair places and they say they don't have the test equipment or spare parts for Pentax anymore.
04-25-2015, 07:30 AM   #3
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Mine is in front of me and it does not have that behavior.

Just convert it to screw drive and save yourself the money. It's only a tiny bit louder, and it's faster, too.

Instructions are here, but they have a lot of unnecessary parts. You don't need pktether or any tethering software. You just need the right text file name for your camera body with the [OPEN_DEBUG_MENU] text inside it. On the K3, you just stick the card with that in, leave the card door open, and turn on th camera, and you can get into debug mode immediately, then follow steps 3 and 4. Debug mode only launches if the card door is open, so it's not a big deal to leave the file in place, but to be safe, just format the card afterwards.
(on a mac, use TextWrangler instead of Notepad++ or Textpad on Windows)
How to deactivate SDM and allow for screw drive autofocus with DA* 50-135mm f/2.8 - Le site des amateurs de PENTAX

it does *not* work for the 60-250. I wish someone would figure out what has to change to make it work on that, because I'd rather have the faster focusing.
04-25-2015, 07:37 AM   #4
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If you want to convert it to screw drive there is a member here who will do it for a small fee.
I love how mine works since i had it converted by him.

He is in so cal ( Palm Springs area.)
PM user Roob-N-Boots

He will just do the conversion though, if the sticking zoom/AF is mechanical in nature that will not be fixed.

04-25-2015, 07:41 AM   #5
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It takes about 5 minutes to do it yourself. Why send it out? That might have made sense back before they figured out how to do it with newer camera bodies for people who didn't have them, but I think every current and past body except maybe the Ks models have been covered now.
04-25-2015, 07:49 AM   #6
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I was under the impression you needed a certain vintage of body to do it.

In any case I preferred to have someone else who knew their way around the process do it quickly and correctly and am willing to pay for that service.

The other day I sent my kindle to have the charge port replaced. There are all sorts of tutorials on utube and the part is a buck or two, but again I was willing to pay for someone experienced to get it done right the first time.

That's just me I guess.
04-25-2015, 10:25 AM   #7
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Thanks everyone. I played with it some more and now think it is something mechanical rather than SDM. The zoom ring gets tighter, almost catching, toward 135 end and that's when the focusing distance in the window changes. I think I will call Precision and talk to them before I send it in.
04-25-2015, 10:34 AM   #8
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QuoteOriginally posted by narual Quote
Mine is in front of me and it does not have that behavior.

Just convert it to screw drive and save yourself the money. It's only a tiny bit louder, and it's faster, too.

Instructions are here, but they have a lot of unnecessary parts. You don't need pktether or any tethering software. You just need the right text file name for your camera body with the [OPEN_DEBUG_MENU] text inside it. On the K3, you just stick the card with that in, leave the card door open, and turn on th camera, and you can get into debug mode immediately, then follow steps 3 and 4. Debug mode only launches if the card door is open, so it's not a big deal to leave the file in place, but to be safe, just format the card afterwards.
(on a mac, use TextWrangler instead of Notepad++ or Textpad on Windows)
How to deactivate SDM and allow for screw drive autofocus with DA* 50-135mm f/2.8 - Le site des amateurs de PENTAX

it does *not* work for the 60-250. I wish someone would figure out what has to change to make it work on that, because I'd rather have the faster focusing.
Have you done this using a K3?

The last time i tried it did not work with the k3 but worked fine with a k7.

04-25-2015, 11:04 AM   #9
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On another note @lenp be sure and join the California user group to keep abreast of any happenings or meet ups.
04-25-2015, 11:07 AM   #10
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QuoteOriginally posted by crewl1 Quote
On another note @lenp be sure and join the California user group to keep abreast of any happenings or meet ups.
Thanks Larry. I'll do that. I check out the club thread once in awhile, but should join it.
04-25-2015, 01:22 PM   #11
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Changing a charging port requires messing with stuff that could get you electrocuted or ruin the device. There's really no comparison between that and modifying the lens file (just don't mess with any other functions and back up the lens file).

I'm pretty sure I did it on the K3, but it might have been the K5.

You can get to the debug menu on k3 with these instructions:
QuoteOriginally posted by Tjompen1968:
Create 2 files in the root of SD card (Make sure your computer shows the file endings, i.e .txt, .PEF, . JPG etc)

00077760.502
DEVELOP.MOD

Open and add the text [OPEN_DEBUG_MENU] to the first file.

Insert the SD card in slot 1 and turn on the camera without closing the card door.

Enable Debug Mode and press OK. You can now remove the files.

In the Menus, before the C1-menu, you now will find a hidden menu.
You'll have to cycle through to menu screen 4 in order to access the lens data:
Lens rom dat camera => SD
lens rom dat SD => camera
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