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08-25-2009, 08:47 PM   #1
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Pentax K20D - vertical bands, noise, and hot pixel problems... :-(

I am very concerned about the health of my Pentax K20D's sensor. Over the past few months, I have noticed an increase in the number of bad pixels, and in the past few weeks I have noticed prominent vertical bands in many images.

My K20D ONLY has an exposure count of 2754, so it is still very under utilized.

In the attached image, a couple of issues bother me:

1. The many vertical bands throughout the photo, and especially the large one to the left side of the photo. These bands now show up in every photo where there is significant enough shadow or lack of detail.

2. The noise! Notice that this is an ISO 200 photo (only under exposed by 1 stop). This photo is screen captured at fit to screen (no cropping). At a 100% crop, the noise is pathetic!

3. Hot pixels on short exposure! Because this photo is sized to fit the screen, the hot pixels cannot be seen. But I did show an example in this thread:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/68129-9-999-999-pixels.html.


Opinions please.

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08-25-2009, 08:58 PM   #2
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Well that certainly made me not push the "buy" button---literally.
08-25-2009, 09:19 PM   #3
Damn Brit
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The bands and the pixels may be unrelated.
You can use the pixel mapping function to correct that issue (Page 235 in the manual).
As for the bands, have you formatted the card? It is best to do that regularly.
Have you tried other cards.
08-25-2009, 09:20 PM   #4
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QuoteOriginally posted by T_MB Quote
Well that certainly made me not push the "buy" button---literally.
Don't leave the house, there's going to be weather.

08-25-2009, 09:28 PM   #5
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Moral of the story....Never buy a used dSLR from an astrographer

Just being cheeky....I don't think you use the K20D for that....
08-25-2009, 11:42 PM   #6
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QuoteOriginally posted by Damn Brit Quote
The bands and the pixels may be unrelated.
You can use the pixel mapping function to correct that issue (Page 235 in the manual).
As for the bands, have you formatted the card? It is best to do that regularly.
Have you tried other cards.
Hey Damn,

The banding is not caused by the memory card. In fact, that would be impossible b/c the image is saved in a digital format (as opposed to analog). If the card were bad, the image would not save correctly, the image would be incomplete, and would load with jpg image errors or not at all.

For sake of argument, I only use class 6 SDHC memory cards and I usually reformat them (in camera) after every backup to computer.
08-26-2009, 12:03 AM   #7
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Here is another example; it is a reduced full frame image. This was just a test photo of the moon at 400 ISO and 1/4 sec exposure. Using Picasa seems to bring out the errors in DNG images without effort.

Doing a quick survey has revealed that the banding seems only visible in about one in every 15 photos and/or if the correct conditions are met.

It seems that I may not be the only one who is experiencing this problem. But of all the other posted examples, mine seems the most severe.
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08-26-2009, 02:51 PM   #8
Damn Brit
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QuoteOriginally posted by pentaxmz Quote
Here is another example; it is a reduced full frame image. This was just a test photo of the moon at 400 ISO and 1/4 sec exposure. Using Picasa seems to bring out the errors in DNG images without effort.

Doing a quick survey has revealed that the banding seems only visible in about one in every 15 photos and/or if the correct conditions are met.

It seems that I may not be the only one who is experiencing this problem. But of all the other posted examples, mine seems the most severe.
Do you have the grip on your K20, they have caused issues in the past?

08-26-2009, 09:53 PM   #9
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My K20 had the power on/off issue when new and was sent away for warranty repairs. When it came back it had the stripe on the left side, that you are referring to....or at least something that was very similar to the image you posted.

It was sent back again and came back fine and has given no problems since. The service report (for what its worth) that came back with the camera made mention of a "mis-aligned" sensor.

If its the same thing then take some heart from the fact that it can be repaired.
Good luck.
Grant
08-28-2009, 06:28 PM   #10
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QuoteOriginally posted by Damn Brit Quote
Do you have the grip on your K20, they have caused issues in the past?
No grip.

The Pentax Forum software told me that my message was too short so that is why I wrote this line.
08-28-2009, 06:34 PM   #11
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QuoteOriginally posted by Mallee Boy Quote
My K20 had the power on/off issue when new and was sent away for warranty repairs. When it came back it had the stripe on the left side, that you are referring to....or at least something that was very similar to the image you posted.

It was sent back again and came back fine and has given no problems since. The service report (for what its worth) that came back with the camera made mention of a "mis-aligned" sensor.

If its the same thing then take some heart from the fact that it can be repaired.
Good luck.
Grant
I am ready to kick some Pentax a$$!

I was told that because my warranty has just expired (I estimated the apx. day I purchased my K20D), the repair would cost $589.00. #$$%^#.... first of all, it is a manufacturer flaw, second... the warranty JUST frigg'n expired. The person I spoke with offered no consolation whatsoever! He told me it was a good value considering the new replacement model is more than double the price. HUH???

This may be the "straw that broke the camel's back" for me.
08-28-2009, 06:35 PM   #12
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That sucks mate, sorry.
08-28-2009, 06:42 PM   #13
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This is a shot in the dark. But based on a recent thread, it could be light making it through the viewfinder onto the sensor that is messing you up. Try blacking out the viewfinder during exposure and try to recreate some of these photos as a test to see if it helps at all.

Jack
08-28-2009, 07:37 PM   #14
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QuoteOriginally posted by jbinpg Quote
This is a shot in the dark. But based on a recent thread, it could be light making it through the viewfinder onto the sensor that is messing you up. Try blacking out the viewfinder during exposure and try to recreate some of these photos as a test to see if it helps at all.

Jack
Although that is an interesting (outside the box) idea, that cannot be the problem b/c the problem showed up in the test photo of the moon as well. I can assure you that there was no light behind me when that image was taken.

I am unsure if I mentioned this but the problem is intermittent and as evidence, I took a number of images of the moon, all similar 1/50 sec exposures. Of the eight photos I took, only three exposures had the vertical lines.
11-29-2009, 01:10 AM   #15
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Has anyone else experienced this problem?

Pentax replied back with a terse message stating that b/c my camera's warrentee expired (a few months ago), the repair cost will be $650.00.

I will reserve my opinion.... otherwise I will likely break forum rules!
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