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Old Apr 27, 2008, 10:21 AM   #11
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Hi Harriet.

I did shoot focus charts and the k100 was much sharper wide open and at all apertures up to about f8than the k100 wiht the Sigma 100-300 EX f4.

The K10 with the DA16-45 was pretty good at larger type scenes but that is a less demanding application of critical focus.

Dennis
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Old Apr 27, 2008, 10:39 AM   #12
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The Pelican photo is exactly the issue I had with my K10D and I finally sold it because I couldn't trust the camera with photos like yours that I couldn't do over. Most times it focused properly, but it would then for no reason BF, so I stopped using it.

I had the first one replaced by Pentax, but it started again with the new camera, although both of my K10D's were early versions. From what I read, the issue may have been solved with later versons of the camera.

Tom
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Old Apr 27, 2008, 4:22 PM   #13
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I also thought I had focus problems with my *ist DL2 and did some focus chart shots, sent the camera to service but they said it's me and everything was ok... hm. :?

But still asking pentax for support is a good idea.

Another thing I read somewhere else is the AF behaviour. In another foto forum someone said that AF roughly works in a f/5.6 DOF range. I first didn't understand but after a while this is what I think he meant: regardless of the f-stop you choosed the camera itself signals "correct focus" if it finds a "sharp" area within the AF area AND the DOF a f/5.6 would give. Using much smaller apertures would result in a "unreliable" AF because the DOF for f/2.8 (example) is much smaller and sometimes you get unlucky...

If that's correct you shouldn't have that behaviour at f/8 for example.

Nextthing I found is that some lenses have a much smaller "correct focus" area than others, especially my Vivitar 28-105/2.8-3.8 has kind of only ONE setting to lighten the AF symbol at a specific target, where other lenses have a small area where you can turn the focus point back and forth and still the camera says "in focus". (Hard to explain - I hope it makes sense in some way to you)

Regards,
Th.

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Old Apr 27, 2008, 6:20 PM   #14
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Tom and TH,

Thanks for your inputs. I've really tried all kinds of stuff to alleviate this. I'd even make the camera focus on something at the other end of the distance range and then focus back and it really didn't seem to help. If I wasn't using a tripod on so many of these out of focus shots it would be another matter. I even did a seried with the remote with MLU and it didn't help either.

I amreallylooking forwardto getting the camera back and testing it.

Dennis
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Old Apr 28, 2008, 12:26 AM   #15
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well it looks as though i have a user error,
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Old Apr 28, 2008, 6:02 PM   #16
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What appears to be strange with the focusing isn't necessarily 'front' or 'back' focus BUT that the birds to back AND front appear to be in focus.

I would have thought that with a front or back focus problem only one set of birds either in the front or back would be sharp - I've never experienced a situation where the subject either side of the focus point is sharp.

Or have I missed somethig along the way - perhaps it's a bit of an optical elusion and that the birds to the left & right are at similar distances from the camera.
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Old Apr 28, 2008, 6:21 PM   #17
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IW,

Yes it is a bit of an optical illusion. All the birds are farther away than the one in the middle, probably by several inches to a foot.

If it was something like you said I have no clue what would cause that unless it was the lens but the lens is sharp on my other body.

Thanks for your input, though!

Dennis
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Old Apr 28, 2008, 6:29 PM   #18
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It's hard to say - if you look closely at the fence, the pelicans that appear to be in front of the center bird are on a fence that is behind the pilons that the other birds are on. Did you take this with a 300mm or longer lens? If so, it'll be hard to judge how close those two fences are due to the perspective compression with a long lens- it's possible that they are further from the camera than the center bird, though it sure doesn't look that way. Do you have any other pictures that show the problem, where you know what the distances are? Unfortunately, I don't think this one is completely conclusive. And I suppose you could have a smudge on your lens - I've had that happen too, by the way. Not that I believe that'sthis problem, but it is possible.

I sometimes wondered about my K10, whether there was something else going on besides focus issues because I thought sometimes the center of the picture wasn't in focus, but the sides were. I never could pin it down, because whenever I shot walls (either brick ora donor wallwhich hadwriting on it) it was fine, and if you are photographing a building from fairly far away, there's differences in distance. I found it all very frustrating because I was never completely sure whether the problem was the camera or me until I got the K20, and the problems went away.

Dennis - let us know how your camera is when you get it back.
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Old Apr 30, 2008, 10:29 PM   #19
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Well, I think my K10D is fixed. I got it back yesterday. The repair says "replacement or adjustment of electronic autofocus circuit including focus motor and encoder, ccd focus device and laser alignment of mirrors. Out of warranty, this service is $260 bucks.

They also cleaned, lubed and adjusted the camera. The time and datewas returned to 2006, exposures were at 14 and the version seen through Photome is 8.1 Vs. 2.1 when I sent it in.

Also, I think there may be some new functionality in the iso adjustmenthaving more steps. I may have missed this before but I don't remember seeing anything like that when I originally set up the camera.

I went to a park near where I live hoping to get some kind of opportunity to take a few pics. This is a loggerhead shrike.This is handheld in raw 300mm F9 iso400 1/500s handheld. This is cropped some, maybe 40%. I don't think I ever got results from the K10 this sharp before. I think this a major revision in the camera operating system that goes way beyond what could have been done with just firmware!I know this is no great pic but the feather detail is pretty darned good and there is minimal PP on this. Saved for web and one pass of Smart Sharpen.




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Old Apr 30, 2008, 10:55 PM   #20
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That's quite interesting news, though your picture didn't show up on my computer. And $260 is significantly less than a K20, for those like me who got so frustrated that a $1200 camera upgrade sounded like a good deal.
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