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08-11-2011, 06:08 AM   #1
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K-5 stain?

Hello here!

A few days ago I started noticing this blue dot on my photos:

This is a 100% crop@70mm, F32.

It definitely wasn't there a week ago, and appeared on my K-5 after > 2500 shots. There was some dust I removed with a blower, but this small smurf stayed here.

Can that be one of those famous stains? Should I send it back to pentax?

Thanks,
Calimo

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08-11-2011, 06:12 AM   #2
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Hi,

It looks like a stuck / broken pixel to me.
No problem, it happens all the time with all / most camera's.

Map it out using the the pixel mapping option in user menu 4.

Cheers, Bert
08-11-2011, 06:32 AM   #3
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Agree with bymy. Looks electronic and not optical and definitely not like any sensor stain I have seen. Most real stains resemble a "string of pearls" and not just one dot.
08-11-2011, 06:52 AM   #4
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Stains



All that I have seen are in groups of some sort. Most are the infamous String Of Pearls. Mine (camera has been replaced) were a little more severe. I agree with the others. Try the pixel mapping routine. None of the stains I've seen had Color to them. Only shades of gray.



08-11-2011, 09:42 AM   #5
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Thanks a lot folks for your answer!
QuoteOriginally posted by bymy141 Quote
Map it out using the the pixel mapping option in user menu 4.
I did that and apparently it disappeared.

But now what is left? I mean, there were apparently more than a dozen of pixels, what are they filled with now? Is there a "gap" in my pictures?
I didn't see anything yet, but as my camera is under warranty, should I send it anyway?
08-11-2011, 11:13 AM   #6
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QuoteOriginally posted by Calimo Quote
Thanks a lot folks for your answer!

I did that and apparently it disappeared.

But now what is left? I mean, there were apparently more than a dozen of pixels, what are they filled with now? Is there a "gap" in my pictures?
I didn't see anything yet, but as my camera is under warranty, should I send it anyway?
The information is just filled in by surrounding pixels. Unless you know the exact location you won't ever see it (and even then, I doubt it) at less than 800% zoom. Sensor stains were not On the sensor supposedly but on the filter glass that Covers the sensor, between the sensor and the filter. What we believe happened was that, especially with using live view, the stain would become baked into the filter glass (coating) over time. Those that use LV religiously saw the stains sooner than others. At the time I discovered mine, I Had in fact been using LV quite a bit.

Manufacturers have a percentage (I don't know what it is) but 12 pixels in a field of 16,000,000 + is nothing and I doubt it approaches the replacement threshold.

08-11-2011, 12:05 PM   #7
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Ok thanks a lot for your help!
Calimo
08-11-2011, 01:23 PM   #8
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QuoteOriginally posted by JeffJS Quote
The information is just filled in by surrounding pixels.
Manufacturers have a percentage (I don't know what it is) but 12 pixels in a field of 16,000,000 + is nothing and I doubt it approaches the replacement threshold.

Strange that TV manufacturers can't do the same type of pixel correction. Or, if they do, I am unaware of it. I couple years back I bought a large screen LCD TV. As soon as I plugged it in a bright green spot appeared toward the center of the screen. Funny that the manual even mentioned that "hot" pixels are common and would not be considered a defect for the TV. Defect or not, it went back to the store for an exchange with a different brand. Both were major brands, i.e. Samsung and Sony.

08-11-2011, 01:32 PM   #9
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QuoteOriginally posted by lammie200 Quote
Strange that TV manufacturers can't do the same type of pixel correction. Or, if they do, I am unaware of it. I couple years back I bought a large screen LCD TV. As soon as I plugged it in a bright green spot appeared toward the center of the screen. Funny that the manual even mentioned that "hot" pixels are common and would not be considered a defect for the TV. Defect or not, it went back to the store for an exchange with a different brand. Both were major brands, i.e. Samsung and Sony.
I had one on my tv a few months back, or I thought I did. I looked for a pixel mapping routine, couldn't find one (the TV is 4 years old). It just simply disappeared. I don't know if it was just Stuck or if it was in fact bad and the TV runs a mapping routine every so often. Visio 39" LCD. While it was there however, it was extremely annoying. Wonderful age we live in. Digital broadcasts that don't work for shit without cable (I wonder how many palms got greased in that transition ), televisions that don't work without remotes, and screens where one little dot can spoil the entire thing.

08-11-2011, 04:22 PM   #10
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Definitely a hot/dead pixel that should be able to be mapped.
08-12-2011, 12:57 AM   #11
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QuoteOriginally posted by lammie200 Quote
Strange that TV manufacturers can't do the same type of pixel correction. Or, if they do, I am unaware of it. I couple years back I bought a large screen LCD TV. As soon as I plugged it in a bright green spot appeared toward the center of the screen. Funny that the manual even mentioned that "hot" pixels are common and would not be considered a defect for the TV. Defect or not, it went back to the store for an exchange with a different brand. Both were major brands, i.e. Samsung and Sony.
No, it is not strange at all.

Actually, mapping hot pixels out on a camera is not turning off/on something in hardware, but something in software.
You are not looking at your sensor, like you are looking at a TV screen.
The sensor is an input device, while a TV screen is an output device.

The output of your camera is a "file" with pixel data. *A lot* of processing is done between the image captured by the sensor and the file produced.
If a pixel is marked dead or hot, it can be mapped out. Software will replace it by the average result of the surrounding pixels, or something like that.

There is no way you can turn off a hot pixel on a TV screen.
If the pixel hardware is broken, the status of that pixel cannot be changed by the driving electronics.
If the pixel could be turned off, it would not have been stuck in the first place.
The same goes for broken pixels, if it could be turned on, it would have been.

Unfortunatly.

- Bert
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