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09-16-2012, 09:56 PM   #1
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K-5 sensor problem

Hi,

I am about to buy a used K-5 with a Tamron 70-300. The seller sent me a couple of sample shots and I noticed the photos have this particular color dot.

I have attached these 2 photos, the dots are circled (I think they're at the same position but the original photos were cropped so I'm not 100% sure).

Is it the problem with the sensor (stuck pixel) or is just the lens?

Thanks.

Attached Images
 
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PENTAX K-5  Photo 
09-16-2012, 09:57 PM   #2
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Probably a stuck pixel, and those will happen to a sensor over time no matter what. You use the "pixel mapping" feature to get rid of them.
09-16-2012, 10:03 PM   #3
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Thanks vonBaloney,

Is that a feature in the firmware? I'm not too familiar with newer models (my last one was K10D)...
09-16-2012, 10:21 PM   #4
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QuoteOriginally posted by Babylon7 Quote
Thanks vonBaloney,

Is that a feature in the firmware? I'm not too familiar with newer models (my last one was K10D)...
Yeah, not sure if they happen on not on the K10D with its CCD sensor, but it is fairly common for a even a brand-new K-7 or K-5 to come with a stuck pixel or two (or anything with a CMOS sensor), and then every once in a while you'll get a new one. You just run "pixel mapping" off the menu and it gets rid of it. (What it does it mark those pixels to not be used in the future and it will average the pixels around it.) On an LCD monitor when the same thing happens, sometimes you can unstick them but don't know if you can on a camera. The easiest way to spot them (they aren't always a bright color) is to shoot a video and create a lot of motion -- just wave the camera around shooting a wall. (Shooting some video might be the strategy to try to unstick them before pixel mapping them, but I have no idea if that would work.) Playback the video on a TV and you can easily see anything not moving with the rest -- dirt on the sensor will show up as well as fixed spots.


Last edited by vonBaloney; 09-16-2012 at 10:30 PM.
09-16-2012, 10:22 PM   #5
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QuoteOriginally posted by Babylon7 Quote
Is that a feature in the firmware?
It's under the Setup menu in the K-5:
Setup Menu 4 > Pixel Mapping.

It should do the job.

Maybe you should ask the seller to do it before you buy the camera, then send you a test shot, just to confirm that it has indeed cleaned them up before buying the camera.
09-17-2012, 05:45 AM   #6
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QuoteOriginally posted by vonBaloney Quote
Yeah, not sure if they happen on not on the K10D with its CCD sensor, but it is fairly common for a even a brand-new K-7 or K-5 to come with a stuck pixel or two (or anything with a CMOS sensor), and then every once in a while you'll get a new one. You just run "pixel mapping" off the menu and it gets rid of it. (What it does it mark those pixels to not be used in the future and it will average the pixels around it.) On an LCD monitor when the same thing happens, sometimes you can unstick them but don't know if you can on a camera. The easiest way to spot them (they aren't always a bright color) is to shoot a video and create a lot of motion -- just wave the camera around shooting a wall. (Shooting some video might be the strategy to try to unstick them before pixel mapping them, but I have no idea if that would work.) Playback the video on a TV and you can easily see anything not moving with the rest -- dirt on the sensor will show up as well as fixed spots.
Thanks, I will the video shooting a try.
09-17-2012, 05:49 AM   #7
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QuoteOriginally posted by rawr Quote
It's under the Setup menu in the K-5:
Setup Menu 4 > Pixel Mapping.

It should do the job.

Maybe you should ask the seller to do it before you buy the camera, then send you a test shot, just to confirm that it has indeed cleaned them up before buying the camera.

The seller doesn't like to answer any of my questions with a straight answer, so I probably need to do it myself. The only reason I am buying it is because the offer is too good to be refused (I think there should be at least several months of warranty remaining).
09-17-2012, 07:32 AM   #8
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QuoteOriginally posted by Babylon7 Quote
The seller doesn't like to answer any of my questions with a straight answer
Red flag.

QuoteQuote:
The only reason I am buying it is because the offer is too good to be refused.
And another. Be careful out there...

09-17-2012, 07:54 AM   #9
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QuoteOriginally posted by vonBaloney Quote
Red flag.

And another. Be careful out there...

Will let you know how it goes - but CAN$650 for the 10-month old body (8000 clicks) and Tamron 70-300 LD. Warranty not transferrable so this is a risk...
09-17-2012, 06:06 PM   #10
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QuoteOriginally posted by vonBaloney Quote
Red flag.

And another. Be careful out there...

Happy to report the camera is solid, pixel mapping cleared up the stuck pixels.
09-17-2012, 06:20 PM   #11
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QuoteOriginally posted by Babylon7 Quote
Happy to report the camera is solid, pixel mapping cleared up the stuck pixels.
Cool. Check everything else...
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