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07-28-2015, 06:57 PM   #1
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Problem with 18-135mm f3.5-5.6 wr lens

Hi all.
I'm new to the forum and would like as the forums advice.
I have Pentax 18-135mm ED AL DC WR lens with a problem. The auto focus won't work anywhere below about 35mm. Works fine for higher magnifications. I have two K5 bodies and the problems is the same for both so I don't think it is the bodies at fault.
I have looked at the DIY SDM repair for the DA* 16-50mm lens and was wondering if this proceedure is the same for the 18-135mm.
Any help would be appreciated.


07-28-2015, 07:19 PM   #2
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The 18-135 is not an SDM lens.

---------- Post added 07-28-15 at 10:21 PM ----------

You're not trying to focus closer than the minimum focus distance are you?
07-28-2015, 07:30 PM   #3
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Thanks for the reply Bunch.
No, it's a problem with general focusing e.g landscape type photos
07-28-2015, 08:06 PM   #4
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While the 18-135 has been quite reliable there have been some instances of it refusing to focus. I had one that stopped focusing completely, was repaired three times and finally replaced by RIcoh. That is rare but it has happened. There was a thread here not too long ago with several people mentioning it not focusing at certain focal lengths. When mine broke it would not focus in manual either.

However, before you assume the worst test it out in good light with a sharp contrasty focusing target. Sometimes there is just not enough contrast to allow it to focus. You might also try it with Liveview focus and see if you get the same results.

07-28-2015, 08:30 PM   #5
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Mine sometimes fails to focus for FL <= 35mm.
Its been discussed on another posting but in summary for my issue:
* The problem is sporadic. Sometimes when it happens I can clear it by zooming rapidly in an out a few times - but other times its more stubborn.
* When problem occurs the lens can still focus but just wont focus on anything beyond about 6m (6 yards).
* It seems to be mechanical because when it happens I also can't achieve infinity focus manually.
* Crude work around - manual focus as far as it will go and stop down to f11 (if I can).

If its in warranty I would send it in for repair (mines way out warranty unfortunately).
08-12-2015, 06:30 PM   #6
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Live view

Hi All
Sorry to take so long to reply to your posts, but I've been sooo busy that I just haven't had the time to fiddle with the K5 and lens.
Anyway, today I thought I would try jatrax's suggestion and use liveview. Guess what? It works fine. This of course is great, but it doesn't solve the problem of through the view finder focusing. It doesn't seem to make any difference what lighting conditions I try with the exception of very low light. Under very low lighting it once again seems for the most part, to work OK. I'm still baffled at this. I prefer to use through the view finder focusing, so it is important that I solve this.
Thanks again for all your suggestions.
08-13-2015, 07:22 PM   #7
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I experienced a similar problem. My lens would focus when I lightly pulled the end of the barrel towards the camera body. I fixed the inability to focus at wide angles by taking the lens apart and tightening loose screws on the barrel. One screw was stripped so I fastened it in with JB Weld epoxy.

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