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10-30-2012, 03:23 PM   #16
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QuoteOriginally posted by mxlinn Quote
Well, guess not everyone kept their gear as pristine as yours. Even the copy you sold me was back focused, still loved it!
I'm sorry to hear that. I didn't have any front/back focus issues with that lens when I owned it.

Just trying to be helpful here - since it seems this is the 3rd of the same lens and you are still have focus issues, have you looked at the possibility of it being a problem with the camera? Are you having similar issues with other lenses as far as focusing? The reason I ask, is that when I first bought my K-5 the AF was fine. After a bit of time, I started noticing a problem with back focusing. I first noticed this with a DA*55 lens which is also a very sharp lens like the 100WR, and then also with a couple new Sigma lenses. I took the time one day to test all my lenses (like I posted above), and found all of them to be off in one degree or another. Making a long story short, I ended up sending the K-5 to CRIS for a warranty repair for the auto focus. It came back and focused perfectly with all my lenses without any AF adjustment.

Just a thought - it might be the AF is off in the camera. There were a few members here that had similar issues with their K-5's and also sent them in and came back focusing perfectly.

10-30-2012, 05:11 PM   #17
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Please, you don't owe me an apology. It wasn't a big deal. Langkata owns your lens now and it appears that he's enjoying it with some adjustment.

This is entirely possible my K-5 is off but can't be certain as my other lenses seem working just fine with it. I understand having 2 copies of D-AF 100mm with back focus seem unlikely, and both previous owners claimig not having issue start make me wonder if my K5 is the problem.

Thanks for the tip and I'll look into it further.
10-30-2012, 06:43 PM   #18
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Took me a while, but I finally found my thread about my AF issues with the details of sending it in for warranty repair. There is also a lot of good information from other members in there. I don't know if your issue is the same or not, but maybe it will help with narrowing it down. If you are still in the warranty period it might be worth while to send it in like I did - at least then it would take the camera out of the equation.

https://www.pentaxforums.com/forums/pentax-k-5/180191-k-5-auto-focus-issue.html

The issue will always be worse with the sharper lenses like the 100wr, and in my case, the DA*55. I did not notice it back then on my other lenses but then I was using more of the consumer grade lenses (DA 55-300, DA 16-45, etc.) and I believe since those lenses aren't as tack sharp it might just not be so noticeable.
10-30-2012, 10:26 PM   #19
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I have the same lens, have had it since new and it does have slight issues at distance, but close up it's super sharp. I can manually focus sharper at a distance but with this lens usually MF most of the time anyway so I don't find it to be an issue. Like others have said the focus points on the K-5 are HUGE and I've had it mis-focus badly many times so I don't rely on it much with this lens.

In fact, here is a perfect example from today walking the dog around the neighborhood. First shot is AF, second is MF. Both are 100% crops. I think it's pretty easy to spot the difference. Distance was about 20 feet or so. All AF shots are usually center-focused unless I'm being artsy-fartsy.







Here's the original MF





Last edited by PushTheRedButton; 10-30-2012 at 11:24 PM.
10-30-2012, 11:49 PM   #20
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QuoteOriginally posted by PushTheRedButton Quote
First shot is AF
But nothing looks in precise focus in that shot - front or back. I can't see any plane of focus at all, just potential camera motion blur.

Second shot looks great - and you can see that the plane of focus is about 30cm deep, in fact more than 30cm if you examine the blades of grass.
10-31-2012, 03:48 PM   #21
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I have three shots using AF that all turned out the same. I think, going back again to the XXL-sized focus sensors, it picked up on something slightly behind the cat despite trying to re-focus multiple times.
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