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11-16-2008, 04:55 PM   #1
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Red and Blue dot in my picture?

I am curious what this may be. This is zoomed in 300% to really show it, but I could easily see it at 100%. This is RAW, PEF, 100 ISO, F/14, 10".

Left, upper (blue) and right lower (red).



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Last edited by jeremy_c; 11-16-2008 at 04:56 PM. Reason: Removed image in body because it is shown in the attached images just fine.
11-16-2008, 05:03 PM   #2
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These are so called "hot pixels" - defective pixels on sensor that "fill-up" more than they should.
It is normal to see some hot pixels on high ISO and/or long exposures. Most RAW converters either map them out automatically or have some option of doing it.
11-16-2008, 05:04 PM   #3
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They look like hot pixels: photosites that'll always register 100% regardless of the image. Try taking two pictures, one fast with the lens cap on and one slow with the cap off. The idea is to get images as close to no light and 100% overexposed. Then you can see what specifically is happening.

I had an old camera that did this in a number of places. I don't remember the exact process, but I took a sample image (all black except the hot pixels), made it transparent, and used that to filter all the pictures I took with the camera. The end result was a 50% gray at each of the hot pixels. Not great but not noticeable unless you're looking for it.
11-16-2008, 05:39 PM   #4
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JPEG processing amplifies the hot pixels and makes them look worse.

However, since you have a K20D you can map out the hot pixels. Take a peek at the manual regarding how it's done.

11-16-2008, 05:42 PM   #5
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QuoteOriginally posted by Ole Quote
However, since you have a K20D you can map out the hot pixels. Take a peek at the manual regarding how it's done.
Is this normal though? I mean, I *just* purchased the camera. If this is normal, than I can go through the mapping process, but I don't wish to map out hot pixels out of a brand new camera if that's not the norm.


11-16-2008, 06:55 PM   #6
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Many electronic devices have hot pixels right out of the box. Manufacturers do not even warranty it as a defect unless you have a certain number of them, or a clump of several.
11-17-2008, 08:45 AM   #7
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It's pretty normal to have a few defective pixels out of the 14600000 (15100000 total) or so pixels of the K20D.

If you're shooting RAW, your RAW conversion software will most likely take care of it anyway, so don't worry too much about it
11-17-2008, 09:19 AM   #8
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I had the same thing with hot pixels and can tell you don't need to worry about, because if you have function in camera to map out hot pixel the do this and every thing is gonna be okay, because you will nod do eny damage to your camera if you use the finction which the camera offers.
It's like this the pentax have much more problems with termic noise than canon or nikon thats an issue, so that means it has a lot more hot pixels especially in long exposures with noise reduction turned off, but that is not the problem if you have time to wait up that the camera is doing dark frame job wich take as long as the exposure was lasted. Now I have nikon d90 and I can tell you that I didn't find a single hot pixel in 5min exposure with noise reduction off.
Before I had pentax k200d and I must say that is the best camera for the price and that I didn't had problems with hot pixel at short exposures, just at long exposure I had to wait the care to do the second shot with shutter closed, that it.
And I must say that pentax like k200d makes good cameras, better than sony, olympus, even better than canon(exept the proffessional model), the same with nikon, but it's having problems with hot pixels, for some that isn't annoying(for me isn't), but if you taking a lot of pictures on BULB, then is only problem that you must have noise reduction turned on because is so many hot pixels, that you can barely recognize the photo that you have made.
Thank you, Sorry for mistakes because mostly I don't speak english(from Slovenia)


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