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11-07-2011, 07:53 AM   #1
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DA 16-45mm AF issue

I love my DA 16-45. It has ver good sharpness for a zoom. And it renders colours very well.

But recently I've discovered it has some auto focussing issues. Only at infinity on the wide end, say at 16mm to 20mm, it has trouble locking focus.

When I press AF it goes: *Click!* -> retry -> *click!* -> retry -> *click!* -> retry -> focus lock. The number of retries varies a lot.

Lighting conditions seem to be of no influence at all. It operates just as bad in bright light, as it does in the shade or dark.

I could be wrong, but I have the feeling that it can't quite reach infinity.

Anybody any experience with this? Any info? Is there something I can do myself?

I'm not very afraid of limited DIY repairs. It's warrantee expired a long time ago, with the previous owner. So, I would welcome the option of fixing this myself.

11-07-2011, 08:00 AM   #2
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I had a similar problem with my 18-55 on my k110d, and found that it wouldn't pull back in from infinity to close focus.
11-07-2011, 08:20 AM   #3
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I have the same problem with the DA 16-45 mm lens on my K-7 camera, it also behaves that way on my K10D. That is the lens would not auto focus lock at the wide end at infinity. On my K200D however this lens does not have this auto focus problem.

The DA 16-45 mm lens will auto focus better at the wide end on the K10D and K-7 when the scene has more contrast.

I also have an FA 24-90 mm lens that will not auto focus all the time at the wide end at infinity on the K10D.

All my other lenses auto focus okay on all three cameras.
11-07-2011, 08:40 AM   #4
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Yes, my 16-45 started acting up a few months ago on my K10D. You're not alone, as it was briefly discussed here: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/147481-odd-foc...da16-45-a.html. I've used this lens for some time without problems, but now this happens often, especially in a bright scene without a lot of contrast.

I'd like to find out if anyone has been able to solve this too.

11-07-2011, 12:26 PM   #5
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Gee, I'm not alone, that's for sure. Hopefully that's a good thing and somebody with a solution will chime in.
11-24-2011, 06:03 AM   #6
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Just a bump. I'd really like to fix this.
05-13-2013, 04:51 AM   #7
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I know this thread is old, but searching the web, I couldn't find any definitive information regarding the exact cause of the problem with the focusing of the lens between 16 and 20mm, or any possible fixes for the problem. I bought mine second hand, it seems to be in very good condition, nothing loose etc, but as I bought it mostly for the 16mm and better IQ than my 18-55WR, I find it a bit annoying...I used it on my K-x when the focus confirmation hexagon at infinity, just flickers, but don't lock, thus no shot in AF. Shots between about 2 and 6m with lots of contrast and light at 16mm also is a sort of a hit and miss story, sometime it will fire, but most of the time not. I haven't had a chance to try it on my K-30 yet. Aperture settings on the lens don't seem to have any influence on the situation.
Have anyone found a reason or cure for the problem?
05-17-2013, 04:20 PM   #8
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I don't own the 16-45, but it has chip built-in which sends serial digital information about its status to the body.

If something (chip, communication path) is disturbing the exchange of information (damaged chip, increased resistance/damping on the path), this could "smear" the bits and lead to occasional uncorrect information for the body.

I forgot which pin it is (it's only one for this communication), but the information can be found somewhere in this forum. If both contacts on lens and body are sitting a bit deep, or suffer from a slight, not visible oxidation, such a behaviour would indeed only occur with a certain lens/body combination.

Just an idea, but maybe you can work from there on.

I think the 16-45 puts the most torque on the mount at 16mm, this could explain why it happens just there. But it doesn't explain why it is only near infinity. Maybe there are 2 faults, independend from each other? Having worked for more than 28 years in analysing quality control problems, I would never disregard this possibility

Of course there could also be a problem with the elements which tell the chip the actual position of the distance setting. But in this case, the error should be the same with all bodies. However, it could explain the infinity case.

05-17-2013, 09:51 PM   #9
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Thank you, I'll have another go at it later today, this time on my K-30, and see if a different camera solves the problem.
05-18-2013, 08:46 AM   #10
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My 16-45 does this also. It did it on a k10d but not a k7. It does it on my k5 also. I just zoom to 45mm and focus and the zoom back out to 16mm. It remains in focus and takes the shot.
05-18-2013, 11:47 PM   #11
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I shot about 900 photos yesterday with it on my K-30, no problems. I'll give it another try on my K-x to make sure it's camera related.
08-23-2013, 04:34 AM   #12
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Tried it on my K-x again, same problem, so it seems some cameras don't play well with the lens...
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