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01-18-2012, 11:13 PM   #1
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Problem with 645D CCD ?

I have noticed this today on my image when I adjusted the contrast and you can see some of it even on the unadjusted image. Has anyone seen this before ?



01-18-2012, 11:27 PM   #2
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I've seen it before, but not on a 645D. It generally indicated a flaw in the sensor, and it doesn't look too good- I'd send the camera in and get the sensor replaced if it's still covered by warranty.

Adam
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01-19-2012, 02:37 AM   #3
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I went out to do another test and upon boosting the exposure this is what I see:

01-19-2012, 11:05 AM   #4
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what you have there is sensor split. I actually have a thread here in the forums on the issue.

My sensor also had this issue. I sent it to pentax and they upgraded the firmware. For whatever reason that seemed to have taken care of the issue. I can no longer reproduce it....but if it comes back up its going back for a sensor replacement. Funny thing is, the shot i noticed my sensor split issue was also taken at Valley View in Yosemite. I noticed it while doing a black and white conversion of this picture: http://www.flickr.com/photos/14288454@N07/5498274600/

Also what ISO are those shots taken at?

01-19-2012, 11:09 AM   #5
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At 100iso, I have another issue with a dead row of pixels in the blue channel above 800iso I need to investigate. It does not show up in most shots but once in a while it's visible.
01-19-2012, 11:12 AM   #6
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Call up Pentax. Ask to speak with Mark Davis. I literally got my camera back this week but haven't really had a chance to fully test it out. I may actually do a long exposure like you did to see if its an issue.

BTW my issue also seemed to happen in the blue channel. I really only noticed it when boosting the exposure on blue skies
01-19-2012, 11:29 AM   #7
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Do you have a link to your split sensor thread ? I'm currently In Yosemite and won't be back home in Canada until the end of the month so I guess i will have to live with the problem somehow. I have done a few other long exposures before and can't see the issue on those images.
01-19-2012, 07:27 PM   #8
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It has happen with my 645D on long exposure at night from time to time. I think it might have something to do with the readouts are independent on each half of the sensor and when there is a color differential in the scene from one side to the other, you get a split.

This never happens with daylight exposures. And most night exposures are fine.

Shuttershane, did Pentax give a reason for the uneven readout?

01-20-2012, 04:17 AM   #9
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This has also happened with my 645D - it's starting to seem like a pretty common problem. The camera has been in Japan for two months and I'm getting it back next week after "service, cleaning and re-calibration".

In my case, the problem also appeared with long night exposures (of the aurora, in Norway) and 2 shots out of about 60 were affected.
01-23-2012, 12:05 AM   #10
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I also had this problem and one or two threads here last year before getting the problem resolved. And by resolved i mean brand new camera, not "sensor replacement".
11-29-2012, 07:36 AM   #11
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i also have similar thing...towards the edge of the frame, here is detail...it appears from 200iso onwards, on 100iso it's gone, which is not really consolation...someone said that repeated mapping solved it but i tried it dozen times...CRISCAM said i can send it directly to Japan to save some time. did anyone sent to Japan directly, any contacts? i have US warranty but they said it should be fine...
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11-29-2012, 12:21 PM   #12
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This is a very uneducated guess....but since the readouts of each half of the sensor are on seperate channels, is it possible that it takes the combination of long exposures and cold climate, to effect this phenominon (issue). In other words, very cold temps cause each channel to be read with slightly different timings...therefore they are not in sync" with respect to the other and also the longer the exposure goes for, the more the descrepancy between the respective readout timings (or differences). Very short daylight exposures in cold weather are not long enough to to effectively see theses miniscle timing differences but longer exposures are. Likewise normal ambient temps do not effect these timing diffferences of the channels, hence, no line down the middle of the senor is seen.

This is not an absolute...as I'm sure there are many excepts and other reasons for this sensor issue.

Dave (D&A)
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