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09-08-2010, 04:49 AM   #1
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Could you please try this for me with k7

Hi all, Here's is what I'd lile you to do. Set the lens to 18mm, iso to 100, and only infinity shots. Those are the conditions under which I'm having the most problems. Under those conditions, if I zoom in to as little as 20mm most of the time it will lock. Now I tried turning up the iso to 250, and the camera locked on just about everything inside, and out! So make sure your shooting at 100iso. I had a friend in Chicago try this with a k7, and he had a very similar experience. He never noticed it before because he almost always has his camera set to iso 400. If your getting the same results, then I would conclude it's totally normal. At 100iso, infinity, and shooting at 18mm you should discover a much more difficult time locking focus. I am using the latest firmware update.

09-08-2010, 05:46 AM   #2
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Sounds like your lens might have issues, as I've only experienced this behavior when it was dark, and there was little contrast in what I was trying to focus on (I always use spot focus, though- have you tried that?).

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09-08-2010, 06:12 AM   #3
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I think you should take Mark's advice - either it's that (lack of contrast), or it's plain old cream crackered and you need to send it in.
09-08-2010, 06:15 AM   #4
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I'm having no trouble at 18mm, ISO 100.

09-08-2010, 06:53 AM   #5
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QuoteOriginally posted by bfo Quote
I'm having no trouble at 18mm, ISO 100.
Are you shooting on at infinity? I find it odd that my friends K7, and mine are both exhibiting the same thing. thats 2 mint K7's supposedly not operating correctly, yet with the exact same fault. You must make sure your shooting at infinity, set on 100ISO, and at 18mm. If thats the case what are the chances? In very bright light it's fine, but if it's slightly overcast under those conditions, it's a bit of a problem.
09-08-2010, 07:43 AM   #6
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I just spoke with Pentax, and they called there headquarters, and was told that under the circumstances I described focus will be much more difficult especially with focal lengths below 20mm's. that's consistent with what I'm getting. So now I'm really confused. your saying yours is working fine, they say no problem it's normal behavior, don't bother sending it in. What now?
09-08-2010, 07:50 AM   #7
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I have never seen a problem with this and have done plenty of wide angle iso 100 shooting, with 3 different lenses below 20mm too (see signature)
09-08-2010, 09:23 AM   #8
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I've had my K-7 since early May and mostly use the Pentax 18-250mm lens. I shoot lots of landscape photos at 18mm and center auto focus at infinity and have not experienced any hesitation or hunting (except, of course, when there is nothing to focus on).

09-08-2010, 10:33 AM   #9
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I've noticed this behaviour as well, most often with the old (non-HSM) Sigma 18-125. I've since gotten a DA 18-250 and it happens much less often than the Sigma.
As for wider than 18mm, I also use a DA 10-17, which never has an issue focusing.
09-08-2010, 10:46 AM   #10
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No problem for me at all. Sigma 10-20, iso 100, AF.S
09-08-2010, 10:52 AM   #11
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Are you trying to focus in low light?

QuoteOriginally posted by BobRad Quote
the Pentax 18-250mm lens. I shoot lots of landscape photos at 18mm and center auto focus at infinity and have not experienced any hesitation or hunting (except, of course, when there is nothing to focus on).
Same here. Same lens. No problems.
09-08-2010, 11:04 AM   #12
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QuoteOriginally posted by Nass Quote
No problem for me at all. Sigma 10-20, iso 100, AF.S
No problem with 18-55 kit either
09-08-2010, 02:00 PM   #13
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I have decided to pack it up tomorrow, and send it in. I'm also sending in the 55-300mm, it definitely has a decentering issue. It's all under warranty so what have I got to loose. I'll also have them clean the prism as there is a speck in there that does bother me. My next question is how good is this service department? This camera is in mint condition including the rear LCD. I sure hope to get it back that way. Any tips on sending this in would be appreaciated. I'm very unhappy with Pentax right now. I mean the camera , and telephoto lens both have issues!
09-10-2010, 12:03 PM   #14
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Send your camera and lens in. You should get something back that work! The service department in AZ does a good job on my camera and many lens that I've had. I'm not satisfy with my K7 to focus with all the Pentax lens I have before and now I am a happy Pentax shooter.
09-11-2010, 04:03 AM   #15
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So,,, what does (did) ISO have to do with focusing?
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