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12-30-2010, 03:48 PM   #16
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Based on the shot you captured it could be determined that your camera is back-focusing with the lens that was used. The reason is because +20mm is sharper than -20mm.

Of course, this is assuming everything was done perfectly. It is also anyone's guess as to how accurate the test sheet is. I say this because the sheet's accuracy is less relevant when depth of field is thin. In your case, depth of field is wide/deep enough that I don't trust the sheet.

QuoteOriginally posted by kpevav Quote
I received a K-r kit yesterday and have been trying a few shots with the kit 18-55 lens today. It seems as though it focuses pretty well under artificial light, a Verilux "natural sunlight" lamp. (Perhaps I should carry one around with me?) I'm hoping that it is okay.


Attachment 79329


12-30-2010, 03:51 PM   #17
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I believe this shot was near maximum zoom at 55mm, I did a few at different focal lengths. I just did it again and it seemed about right. I also opened up as much as possible.

Two questions. If there is a minor (not severe) front focusing or rear focusing problem, I would assume stopping down a bit will enlarge the DOF and cover the inaccuracy. I thought with most kit zooms that one would wish to stop down whenever possible, although that is a lens sharpness problem rather than an in-camera focusing problem.

Second, how do other cameras compare, both Pentax and others?


QuoteOriginally posted by krebsy97 Quote
What was the focal length for this shot?

It's going to be hard to perform this test with the kit lens since its aperture doesn't open up enough to permit razor thin depth of field.
12-30-2010, 03:56 PM   #18
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Stopping down will, in fact, increase depth of field to a point where imperfect focus will not be visible.

I believe the issue with my sample wouldn't have presented itself with the kit lens.

QuoteOriginally posted by kpevav Quote
I believe this shot was near maximum zoom at 55mm, I did a few at different focal lengths. I just did it again and it seemed about right. I also opened up as much as possible.

Two questions. If there is a minor (not severe) front focusing or rear focusing problem, I would assume stopping down a bit will enlarge the DOF and cover the inaccuracy. I thought with most kit zooms that one would wish to stop down whenever possible, although that is a lens sharpness problem rather than an in-camera focusing problem.

Second, how do other cameras compare, both Pentax and others?
01-05-2011, 05:29 AM   #19
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Here are the results for my brand new Pentax K-r

IMGP0113 | Flickr - Photo Sharing!
IMGP0111 | Flickr - Photo Sharing!
IMGP0109 | Flickr - Photo Sharing!
IMGP0108 | Flickr - Photo Sharing!

I'm devastated...

Is this the same as what you guys are seeing?
Should I take it back to the store or try to get software upgrade from Pentax?

Pictures taken with Pentax f1.4 lens.
Same lens on my old K100 d Super had no problem whatsoever.
My 17-70 f2.8 sigma also shows front focus.

01-05-2011, 06:17 AM   #20
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Return it for some nice glass. That's what I did.
01-05-2011, 06:45 AM   #21
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i'd still need a camera
already sold my k100dSuper
01-05-2011, 07:11 AM   #22
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How about a k-x? It is quite similar, and I can't recall seeing much related lamentations.
01-05-2011, 01:01 PM   #23
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Hi, I've same problem. I still can take it back to the store, but I like this camera.
Is this problem fixable with soft update? And are there K-R users without this issue?

01-05-2011, 01:34 PM   #24
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It sounds like the K5 has the same problem with front focusing.

As far as whether or not it can be fixed via firmware update is anyone's guess. I personally don't feel good about it. Having said that, if it's not hardware related there's no reason why new software couldn't fix it.

QuoteOriginally posted by Keton Quote
Hi, I've same problem. I still can take it back to the store, but I like this camera.
Is this problem fixable with soft update? And are there K-R users without this issue?
01-05-2011, 03:20 PM   #25
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As I gather from forums only a percentage of the k-r s have the problem.
I've just sent mine back to the store, i'll let you know if they come up with a solution.
I'm hoping for a working replacement, except for the focussing problem the k-r seemed like a great camera to me.
01-09-2011, 10:56 AM   #26
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QuoteOriginally posted by Etown Quote
i'd still need a camera
already sold my k100dSuper
I never sell my cameras, even the old ones..
12-22-2011, 06:41 PM   #27
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Hey guys, I'm still new to this, just got my first camera the K-r a month ago. how would I know if my k-r has focusing problems too?
12-22-2011, 08:43 PM   #28
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On the chart pics, what is the distance from front element to "this line should be in focus"? Min focus or something significantly greater?

Kaiserz, if you're shooting kids across a room at F5.6 Front Focus will not be evident. where it becomes a concern is with faster lenses shot wide open at close focus (which produces a very thin "in focus" range).

You might find the following link of use to understand Online Depth of Field Calculator Select your model of camera (K-x as there is no K-r listed) and focal and aperture and it will product a near in focus and far in focus range. For K-r + FA50mm F1.4 at minimum focus distance shot wide open, the in Focus DOF is only 0.8 cm.

As I said, chasing kids around the house at F5.6 its not going to bother you, but say shooting food photography or similar it could be a problem.

In the attached pic A-100 F4 macro Vivitar 90-230mm F4.5 @ 90mm and F5.6 was used wide open at about 18" distance.. the DOF calculator says my in focus range is only ~ 0.5 cm. I hope that helps give you an idea of what the issue is, and where you find it.

Last edited by mattt; 01-07-2016 at 05:34 PM.
12-23-2011, 09:04 AM   #29
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I tried all the focus charts and didn't like the results. Knowing that the Kr focuses correctly in tungsten lightning using live view contrast focusing. I shot the same image using live view and auto focus using the finder, both shots wide open then adjusted the focus compensation until I got acceptable images. I found that -10 got me very close to correct in tungsten. I did the same for daylight and found that I needed to adjust to +3. I got the same results for 3 lenses 35mm f2.4, kit 18-55 and 55-300 I was happy with the Kr before I did this but even happier now. It might be that my Kr focusing correctly in daylight at +3 allowed my correction -10 for tungsten to work.

Hans
12-23-2011, 10:55 AM   #30
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@mattt Thanks for the explanation. To be honest, I don't really get it... maybe because I haven't encountered the given problem yet, or maybe I'm still too new to recognize. But I have a feeling that I've encountered this so far with my new main lens the DA 35 2.4 Cause 1 out of 5 shots that I take, only one is sharp enough to make me happy(I always shoot at F2.4 but is moving towards f3.5 for a much sharper image). Once again thanks (:
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