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03-08-2010, 09:45 PM   #1
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K7 Focus problem

Hi,
I bought a K7 from B&H thru mail order and received the K7 & 18-55 lens last 21st. First few photos sguggested impoper focus and I tested it thoroughly using many focus testing charts/methods and found the K7 & 18-55 does front focusing. AF adjsutment accoridng to manual didnt even fix the problem. B&H agreed to take this in and send me a replacement.

I have few questions from people with such experience.

1. Is this a common problem with K7 or is this an isolated bad sample?

2. What is the guarantee that I will get a camera without this prolem next time around.

3. Can I request B&H to test the next camera they are going to send me for proper focusing

4. What can Pentax do about this?

Thanks you all for your time.

Ranjith


Last edited by sudupoosa; 03-08-2010 at 09:56 PM.
03-08-2010, 11:57 PM   #2
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Not only is it common, but it's perfectly normal. Each camera is slightly different, and each lens can be slightly off compared to other lenses. This isn't isolated to Pentax cameras, but for any SLR.

On my camera, some lenses require focus adjustment, some do not. The focus adjustment usually works fine, but it takes a lot of testing to get it exactly right. I've found that my kit lens needs no adjustment whatsoever. My DA* 50-135 needs -8 to get the sharpest pictures, and my F 35-70mm needs -3. Luckily, the camera remembers these settings for each lens so it's really not a very big deal.

Focus charts are only useful if you're using either outdoor light or good studio lighting. Under tungsten light, auto focus performance might be unreliable, especially if you're trying to focus on a chart.
03-09-2010, 02:03 AM   #3
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I don't agree that it's perfectly normal. Production tolerances on cameras and lenses should be so that it should always be possible to adjust any Pentax camera (either yourself in case of K20D/K7 or in a service center in case of others) to any Pentax lens. So if a max adjustment does not cut it, it's bad production of either the one or the other or of both.

Just my feeling.

PS I assume that the tests were done properly.
03-09-2010, 03:25 AM   #4
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In all manufacturing processes, you have manufacturing tolerances. It is (so far) impossible to get everything manufactured to a "zero tolerances" standard. When you get a good with all tolerances at their minimum, you end up with something above average. If the tolerances are at their maximum in opposite direction, you end up with substandard material. And then, there is everything in between. Unfortunately, we live in an imperfect world, and we want everything to be perfect.

Instead of returning your camera/lens combo to the seller, you could have sent it to Pentax to have it re-calibrated. You would have lost a few weeks, but it should have been close to perfect then. Or, you can play the Russian roulette, and try a new one hoping it will be within acceptable tolerance, which will likely be the case.

03-09-2010, 06:02 AM   #5
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QuoteOriginally posted by sterretje Quote

PS I assume that the tests were done properly.
BAM!!!
There is no way of knowing if the OP knows how to run a focus test properly, so there is no way to know if he had a problem camera or a problem test.

To the OP, when you get your next camera, don't waste your time on focus charts, go out and take some pictures instead.
If you go looking for problems, you will find them.
This applies to any consumer good you buy, not just cameras.
03-09-2010, 12:06 PM   #6
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QuoteOriginally posted by sterretje Quote
I don't agree that it's perfectly normal. Production tolerances on cameras and lenses should be so that it should always be possible to adjust any Pentax camera (either yourself in case of K20D/K7 or in a service center in case of others) to any Pentax lens. So if a max adjustment does not cut it, it's bad production of either the one or the other or of both.
I just read this article yesterday, it was posted on this forum. Very elucidating:

LensRentals.com - "This lens is soft" and other FACTS
03-09-2010, 09:31 PM   #7
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Original Poster
Thank you all for your posts.

Test was done outdoors
Tripod and relaese cable was used

FYI Please.

Ranjith
03-09-2010, 10:00 PM   #8
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Might help to post the actual test images that led you to conclude focus was off. DOF is pretty deep with the kit lens. It would be extremely rare for the camera or lens to be so far off that you'd be able to notice the difference.

03-09-2010, 10:03 PM   #9
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Same issues

I have had some of the same issues posted here. A couple questions:

Is there a good resource for how to perform focus adjustments?

Does anybody have the best contact info for Pentax to ask them if I can send in for recallibration?

Thanks in advance,
Mike
03-09-2010, 10:12 PM   #10
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QuoteOriginally posted by sudupoosa Quote
Thank you all for your posts.

Test was done outdoors
Tripod and relaese cable was used

FYI Please.

Ranjith
That being the case, and it shows up in real world photos (I don't find the focus test charts to be all that wonderful), then you likely have a body that is out of spec.
It happens. My K20 is adjusted to -10 on several lenses, no lenses are +, and on a couple of lenses, -12 would be nice.
03-10-2010, 11:25 AM   #11
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Ranjith,

I had just finished packaging my K-7 for shipment to the Pentax service center when I read your post. I checked mine the same way using the Nikon standard chart, natural light, tripod, and remote release. The difference is that I also have a K-x and all but one of the 4 lenses that I tested were spot-on with the K-x but 2 could not be adjusted enough on the K-7.

I called Pentax and even though I could still return the camera for a replacement, based on what they said, I concluded that the safest approach is to send the K-7 with the 2 lenses to Pentax for calibrating. I need the camera for a trip next month, so I did not want to take the chance of getting another K-7 with the same problem. One of the problem lenses (12-24mm) required 4 samples before I got one that was acceptable. Since I plan to use that one as the primary for the K-7, that provided more motivation for me to send the lot to Pentax n lieu of trying another K-7.

Good luck with whatever you finally decide to do.

Bob
03-10-2010, 11:34 AM   #12
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Mike,

There should have been a pink slip in the package with your K-7 with the phone number to call: 1-800-234-0276. This is the "DO NO RETURN THIS PRODUCT TO YOUR DEALER" message. That's the number I called. Just send the camera and lenses that are not focusing to the nearest service center (look for this at the Pentaximaging website since the addresses on the documentation in the package may have changed). Check out this site for guidance and a test chart Nikon D70 Focus Chart

Bob
03-10-2010, 11:53 AM   #13
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Thanks Bob
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