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12-19-2008, 04:54 PM   #1
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Sensor Glitch

A short time ago I posed the question "What is wrong with my K200D?" Now I fear I may have a real problem with my sensor. I was shooting some lit icicles outside last night and noticed a bright dot on my pictures. All of them. Upon close inspection it appears that three pixles are somehow damaged. According to the manual if it were dust, it would show up as a shadow on the light parts of the image. Mine has a few bright pixels on the dark part of my images. I attemped to blow off the sensor, to no avail. Attached are the pics. I would really like anybody's opinion as to what it is....More than likely I will be sending the camera to be repaired. I can easily repair the pics in PP, but for being only a few months old, it is covered under warranty, if it is in-deed the sensor. It is actually quite depressing. Getting anything repaired is such a hassle nowadays.

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12-19-2008, 05:47 PM   #2
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It's a burnt/hot pixel. If you send it in to Pentax, they will have your camera for approximately one month. I have a hot pixel on my camera and it JUST came back from Pentax after having been gone a month already for a toasted sensor. I'm not looking forward to the return process once again. Some here might call you a "pixel peeper" and noting that it doesn't appear in print, and to let it go. However, if you're like me, I present many images via a large screen, and such hot pixels distract from discerning eyes (esp. mine). I believe there is an application out there that zaps these upon import, but I'd prefer they simply not be there altogether.
12-19-2008, 07:38 PM   #3
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It's actually normal to have a few hot pixels on any digital camera, and they tend to develop over time, so even if you're clean one day, you might not be a year later. And some pixels may be sporadically hot, with problems showing up only during relatively long exposures.

On the K200D, you can use the "Pixel Mapping" function in the Setup menu to have the camera ignore these pixels. Not sure if that applies to RAW or just JPEG, but many RAW processors take care of hot pixels automatically anyhow.

But really, except when viewing an image at 100% on screen, a few hot pixels are normally not noticeable.
12-20-2008, 12:16 PM   #4
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I used to have a K100D that had hot pixels (and no remapping function), so I started shooting everything in RAW because Adobe took care of it seamlessly. I have never looked back to JPEG since as RAW offers so many benefits.

Are you shooting in RAW or JPEG? I didn't know the K200D had the pixel remapping function, but you should give it a try.

12-20-2008, 02:54 PM   #5
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I just noticed same on my new (received yesterday) K20D. Pixel mapping did nothing, and dust alert found nothing.

And it happens to be right smack dab near center of the sensor!

On dark colored objects, viewing the pic in Vista, zooming in just twice shows a pink spot.
Appears to be a 9x9 (81 pixel) area, and as I said, the darker the color of the object, the more pronounced it is.

Since I just received the camera 20 hours ago, could I exchange it?
Came from Adorama

T
12-20-2008, 05:29 PM   #6
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Hot pixels are a fact of life with digital cameras. Just shoot raw and most raw processors will automagically remove them when the image is processed.

The K20D has a function to map them out in camera, but I've only used it once or twice. I generally don't go looking for hot pixels.
12-21-2008, 05:37 AM   #7
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QuoteOriginally posted by rfortson Quote
Hot pixels are a fact of life with digital cameras. Just shoot raw and most raw processors will automagically remove them when the image is processed.

The K20D has a function to map them out in camera, but I've only used it once or twice. I generally don't go looking for hot pixels.
As wrote above, RAW converters do take care of hot pixels. I've tried PPL, CS3 and LR2. All of the did great job...
just shoot raw, problem solved, enjoy shooting...
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12-21-2008, 09:06 AM   #8
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QuoteOriginally posted by kveldalf Quote
It's a burnt/hot pixel. If you send it in to Pentax, they will have your camera for approximately one month. I have a hot pixel on my camera and it JUST came back from Pentax after having been gone a month already for a toasted sensor. I'm not looking forward to the return process once again. Some here might call you a "pixel peeper" and noting that it doesn't appear in print, and to let it go. However, if you're like me, I present many images via a large screen, and such hot pixels distract from discerning eyes (esp. mine). I believe there is an application out there that zaps these upon import, but I'd prefer they simply not be there altogether.
Your raising the cost of cameras.... almost all sensors have them. Most manuf. map them out before releasing the camera. Pentax has chosen not to I believe...They do have a mapping function on the K20.
If you find a camera without them it is either, pure luck or, they have been hidden from your view.
Next insidious point. They INCREASE over time. Pixels will fail over time so a perfectly pixelled camera will eventually have some. Sorry just the way it works.
Sometimes I feel this is like telling people there is no Santa Claus.....
Oh I suppose I should add that as exposure time increases so do "hot pixels". So it is a dynamic thing and almost impossible to control.

12-21-2008, 10:23 AM   #9
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QuoteOriginally posted by Sharkonwheels Quote
Appears to be a 9x9 (81 pixel) area, and as I said, the darker the color of the object, the more pronounced it is.

Since I just received the camera 20 hours ago, could I exchange it?
Came from Adorama
9x9 definitely isn't normal. It is normal that a single bad pixel would affect it's neighbors because of the nature of how the original RAW image is converted to RGB, but it shouldn't be be 9x9. You might want to post a 100% crop from such an image here to be sure it isn't something else going on, but assuming it is as you say, then definitely, it should be returned - that's not your ordinary run-of-the-mill hot pixel.
12-21-2008, 10:26 AM   #10
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QuoteOriginally posted by Sharkonwheels Quote
Appears to be a 9x9 (81 pixel) area, and as I said, the darker the color of the object, the more pronounced it is.
If you really have a 9x9 hot-pixel area (viewed at 100%) I think you may
ask Adorama to substitute the camera
12-21-2008, 10:28 AM   #11
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Marc, you beated me
12-21-2008, 03:58 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
9x9 definitely isn't normal. It is normal that a single bad pixel would affect it's neighbors because of the nature of how the original RAW image is converted to RGB, but it shouldn't be be 9x9. You might want to post a 100% crop from such an image here to be sure it isn't something else going on, but assuming it is as you say, then definitely, it should be returned - that's not your ordinary run-of-the-mill hot pixel.
Attached are two crops from the JPG's - just opened in MSPaint, cropped a section, pasted in another window and saved.

QuoteOriginally posted by pvanni Quote
If you really have a 9x9 hot-pixel area (viewed at 100%) I think you mayask Adorama to substitute the camera
I would assume the same.

Anyways, let me know what you guys think.
It's in the SAME EXACT spot on all photos, except where the colors are similar in the are where the spot shows up, ie, I took a night pictures of a house's Christmas lights, and it was nigh impossible to find. But sky shots, dark object shots, etc... it is blatantly obvious

T
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12-21-2008, 05:05 PM   #13
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QuoteOriginally posted by Sharkonwheels Quote
Attached are two crops from the JPG's - just opened in MSPaint, cropped a section, pasted in another window and saved.
Maybe I'm missing something, but I can't tell from these it isn't just a single pixel. like a normal hot pixel.
12-21-2008, 05:18 PM   #14
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Original Poster
Now that you mention it, when I first noticed it I was looking at the RAW pics straight from the card. When I imported them into Aperture, most of them went away. I'm not sure how I feel about them being "normal," but I'll wait until after the holidays before thinking about sending the camera in, especially if the camera comes back with other hot pixels. You gotta pick your battles. Thanks for your replies.
12-21-2008, 05:47 PM   #15
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Using the Pentax Photolab, and PEF raw images, TOOL>AutoFix doesn't fix it.
Slight and strong both failed, and actually actually, depending on the contrast against
the surrounding area, makes it worse. It decreased the actual SIZE of the image defect, but uses a brighter color pinkish replacement on the pixels

Only way I've been able to get rid of the defect, is zoom to 4:1 or 8:1 in Lightroom, and
use the heal tool manually. It's a bit much to have to do that to EVERY image...

On the samples above, they happen to be about an 8x8 grid or so. The size varies depending on the contrast,
but the defect is never smaller than about a 7x7 or 8x8 section.

I HAVE used the Dust alert, and it found nothing.
I also tried using pixel mapping, and same results.

One thing I DID notice, is tripping the shutter with the lens cap on, or taking a picture of a VERY black item (audio speaker)
showed no defects. Does that happen to give any more clues?

T
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