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02-22-2009, 11:31 AM   #16
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QuoteOriginally posted by phler2 Quote
Hi,

actually, i had started an other thread after i had received my k20 back from pentax without any changes to it.

that thread has been quite active on the subject, which seems to be quite common, i'm not saying very common, but enougth that there are a few person reporting the same issue

here it is:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/43634-k20d-vertical-strips-7.html

on the bad news, i have had my camera changed, but the new (actually refurbished) one was faulty too... but i know many people shoot in cold conditions without any problems

i have moved to switzerland now, and pentax there seems much more responsive than in quebec. i have sent it back again. we'll see whats next.

Thanks for that, sorry to hear about your luck. I decided to pick up a K20D in a week or so and was hoping that the problem was fixed. However, it seems that now Pentax knows what the problem is.

02-22-2009, 01:51 PM   #17
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Well they seem to be swapping sensors to these broken cameras. The problem might as well be diminishing output levels from the battery in the cold. Perhaps the juice required to pull off a shot and write the data into the memory card in a short timeframe (especially continuous shooting) is too much to handle in extreme temps.
02-23-2009, 01:01 AM   #18
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QuoteOriginally posted by Maffer Quote
Well they seem to be swapping sensors to these broken cameras. The problem might as well be diminishing output levels from the battery in the cold. Perhaps the juice required to pull off a shot and write the data into the memory card in a short timeframe (especially continuous shooting) is too much to handle in extreme temps.

i don't think so, otherwise it would affect things more randomly.
there are two hypotheses presented in the other trhead

one is that it is clock interferes in the ADC (there is a clock much like your cpus gigahertz has one that drives the analog to discreet converteur when reading the sensor). that actually is a know problem in such sensors as the literature exist on the topic

second hypotheses is there are two adc reading the sensor at the same time but both are not initialized with same exposition in certain cases
04-30-2009, 04:51 AM   #19
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Same problem here *FIXED*

Hi,

I just had my camera changed. I had exactly same problem. Every few shots, in cold weather (-6 to -4 degrees C).

The camera was sent also to the Pentax main service center in Hamburg/Germany, but what they did helped very little. (including upgrade to 1.03 and image sensor recalibration)

After the 3rd trip to service they agreed to refund me, and I`ve got a new k20d this week.

As I mentioned before, it was very bad in cold weather, but I`ve read posts that were less temperature related.

It could be just because of a component from the A/D conversion unit, that malfunction because of probably: moisture, cold, electrical interference, etc...

Send it asap to service, that is my opinion about it.

05-01-2009, 11:05 AM   #20
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UGH!!! I just bought a K20D on eBay that has this problem. Here I was all worried about how M lenses were metering on it, only to discover that metering is the least of its problems. I've requested a refund from the seller. I really hope he complies.

05-02-2009, 03:47 PM   #21
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Update

I've done some serious testing with this K20D and am going to report my findings in case they might be helpful to someone else.

The problem for me shows up at ISO 200 only, mostly with underexposed images, and is primarily visible in only the darker regions of the photographs. It is absolutely 100% reproducible. I can get 10 shots in a row with the banding if I shoot at ISO 200. However, it seems to be brought out not only by the dithering but also by sharpening, and the effect is most evident on only one of my two monitors. The latter observation suggests that the effect is a combination of dithering plus a moire produced by the LCD. I don't have a good printer here, so I can't test the combination of dithering + printed dot pattern.

The eBay seller turned out to be a senior member of this forum and was very cooperative. He offered me a refund, but since the problem has turned out to be so minor, I'm not going to bother us both with that process. My main concern was that cold weather would exacerbate the problem, and I have no way of testing the camera in cold temperatures right now. So I asked the seller for his original receipt so that I can make a warranty claim with Pentax in the event that the problem gets worse. He promptly supplied me with the receipt, so I'm keeping the camera and will hope for the best.
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