Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-28-2009, 01:21 PM   #1
Veteran Member
DanLoc78's Avatar

Join Date: Apr 2008
Location: Philadelphia
Photos: Gallery
Posts: 915
9,999,999 pixels

It appears as though my K10D is down a pixel. Is this a common problem? I've had it for about 1.5 years with zero problems. But on a recent vacation i noticed a white spot in the same place in every frame. Could this be sensor dust? Or since it is white would it be more likely that this is a dead pixel?

If dead pixel...any way to remedy this problem? You simply can't tell in any full size images that there is a dead pixel...it just bums me out

07-28-2009, 01:42 PM   #2
Ole
Administrator
Ole's Avatar

Join Date: Sep 2006
Location: Copenhagen, Denmark
Photos: Gallery | Albums
Posts: 3,881
In my experience with my *istD dead, or hot, pixels develop over time. You can send your K10D to Pentax to get the defective pixel mapped out, or you can shoot raw and the raw converter will map them out. I consider you very fortunate if you have just one by the way.

From the K20 the user can map out dead pixels which saves the trip to Pentax.
07-28-2009, 02:17 PM   #3
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
Google the term "dead pixel" or "hot pixel". Pretty much all cameras have them or will get them over time. Good RAW processing programs will remove them in processing. Newer camera models have a facility in the camera to remove them in the in-camera processing as well. But it's still very common for images to have a few.
07-28-2009, 07:19 PM   #4
Veteran Member
DanLoc78's Avatar

Join Date: Apr 2008
Location: Philadelphia
Photos: Gallery
Posts: 915
Original Poster
thanks guys...i'm definitely less bummed now!

07-28-2009, 07:24 PM   #5
Veteran Member
lavascript's Avatar

Join Date: Jul 2009
Location: Baton Rouge
Posts: 390
LCD's get 'em too. Somewhere, I read that you can sometimes get rid of an LCD's hot pixel by mashing on it with your thumb. I had a laptop with one hot pixel, but it didn't work. Later, it developed another, I tried it again, and imagine my surprise when it actually went away!

(No, I'm not suggesting that you mash on your sensor, or that it would even remotely work.)
07-30-2009, 01:12 AM   #6
Site Supporter
pentaxmz's Avatar

Join Date: Dec 2008
Location: Seattle
Posts: 659
QuoteOriginally posted by DanLoc78 Quote
It appears as though my K10D is down a pixel. Is this a common problem? I've had it for about 1.5 years with zero problems. But on a recent vacation i noticed a white spot in the same place in every frame. Could this be sensor dust? Or since it is white would it be more likely that this is a dead pixel?

If dead pixel...any way to remedy this problem? You simply can't tell in any full size images that there is a dead pixel...it just bums me out
My K20D has very recently started displaying hot pixels. Pixel peeping RAWs going back, I found that this begun (for no known reason) about 3 months ago.

The worrying part is that the problem seems like the hot pixel problem is spreading. Now I am counting a consistent 20 bad pixels (on all exposures) and my camera shutter count is under 8000. I know I can map out the dead pixels but the problem isn't actually seriously affecting my photos yet.
Attached Images
   

Last edited by pentaxmz; 07-30-2009 at 04:06 AM.
07-30-2009, 03:58 AM   #7
Veteran Member
ytterbium's Avatar

Join Date: Jan 2008
Posts: 1,076
My k200d had few of them straight out of the box. It is nothing to be worried about in a non scientific grade sensor (read some Kodak sensor data sheets to find out reasonable/tolerable values).

The only thing to worry about is their effect on pictures and possibility to map them out.
Unless your sensor is rapidly gaining them which could lead to complete degradation and indicate a faulty sensor just map them out.

Those images seem to be somewhat noisy. I always get more than those few constant hot pixels at high iso's or with longer exposures, if noise reduction (hi iso) or dark frame subtraction (long exp.) is off. At iso200, 30s DFS and NR off i expect them all over the frame, most of them being very bright (will add a picture later).
07-30-2009, 04:10 AM   #8
Site Supporter
pentaxmz's Avatar

Join Date: Dec 2008
Location: Seattle
Posts: 659
QuoteOriginally posted by ytterbium Quote
My k200d had few of them straight out of the box. It is nothing to be worried about in a non scientific grade sensor (read some Kodak sensor data sheets to find out reasonable/tolerable values).

The only thing to worry about is their effect on pictures and possibility to map them out.
Unless your sensor is rapidly gaining them which could lead to complete degradation and indicate a faulty sensor just map them out.

Those images seem to be somewhat noisy. I always get more than those few constant hot pixels at high iso's or with longer exposures, if noise reduction (hi iso) or dark frame subtraction (long exp.) is off. At iso200, 30s DFS and NR off i expect them all over the frame, most of them being very bright (will add a picture later).
The 100% is from ISO 400 and 1/250 sec.

Most of the time, the hot pixels blend into the photo so I am not concerned (as long as it doesn't spread). The persistent ones (with the arrows) do appear at all ISO's.

07-30-2009, 06:01 AM   #9
Veteran Member
DanLoc78's Avatar

Join Date: Apr 2008
Location: Philadelphia
Photos: Gallery
Posts: 915
Original Poster
what does it mean exactly to 'map them out'?
07-30-2009, 09:35 AM   #10
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by DanLoc78 Quote
what does it mean exactly to 'map them out'?
It means to perform some sort of process that recognizes the bad pixels and performs some sort of software magic to make them not show in the final image. Many RAW processors do this automatically - they notice the bad pixel and ignore it when creating the image. Some might have a mode where you teach the program where the hot pixels are rather than having the software notice them automatically. Some cameras have a built-in facility to do this themselves (K20D and later) - you run the facility from the menu, and it finds the bad pixels. Or you can send a camera in for repair. and the service center has a special program they can use to make older cameras do this too. So that the bad pixel will simply be ignored in constructing your image (and the software that creates the image from the RAW data know to fill in the hole with something reasonable, like the value of the neighboring pixels). I'm not sure how much Pentax would charge to map out bad pixels on a K10D, but if it's just one, again, I wouldn't worry - most camera will have a dozen within a couple of years. If your RAW processing program won't remove them for you, or if you won't shoot RAW, I'd wait until you have a whole bunch of them before putting out the money to.
08-06-2009, 05:53 AM   #11
Veteran Member
DanLoc78's Avatar

Join Date: Apr 2008
Location: Philadelphia
Photos: Gallery
Posts: 915
Original Poster
well I've done some night photography and some very long exposures recently and I've noticed a significant number of what appear to be dead pixels. Way too many to be using the PS spot healing brush. Anyone have any clue what it might cost to have them mapped out by Pentax?
08-06-2009, 06:33 AM   #12
Pentaxian
LeDave's Avatar

Join Date: Jun 2009
Location: Minneapolis - St. Paul
Photos: Gallery
Posts: 2,904
Wow you guys have really good eyes to spot such a small dot, it's hard for me to see much but I can see it when I stare hard enough.
08-06-2009, 08:45 AM   #13
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by DanLoc78 Quote
well I've done some night photography and some very long exposures recently and I've noticed a significant number of what appear to be dead pixels. Way too many to be using the PS spot healing brush. Anyone have any clue what it might cost to have them mapped out by Pentax?
No, but you don't want to map out pixels that only show problems (most likely hot, not dead) when doing long exposures. It's pretty normal for otherwise healthy pixels to go hot on long exposures, as the sensor tends to overheat. That's why the Slow Shutter Speed NR option exists in your camera - so the camera can take a second (blank) exposure right after the first, see which pixels go hot, and map them out for you on that shot only. Mapping them out permanently is unnecessary, since they still work fine at normal shutter speeds.

Also, as I said, most RAW software can map out dead or hot pixels automatically - no reason to resort to spot healing them manually!
08-06-2009, 10:55 AM   #14
Veteran Member
Miserere's Avatar

Join Date: Sep 2007
Location: Boston
Photos: Gallery
Posts: 1,994
My K10D will be 2 years old at the end of the month. I have some 6-8 hot pixels, and they've been there a while. I shoot RAW, so I don't worry about them. I'm sure many new cameras have a hot/dead pixel or two (or more).

By the way...
  • Hot pixel: Will normally shine bright red, green or blue, independently of the colours surrounding it. Usually brighter the longer the exposure or higher the ISO. Also, the longer the exposure and or higher the ISO, the more hot pixels you will see, but some will be there no matter how short the exposure or low the ISO; these are generally termed stuck pixels.
  • Dead pixel: Will be black always, independently of the colours surrounding it. This is less frequently visible because images are created by demosaicing the RGB Bayer array of pixels on your sensor, so a single dead pixel gets averaged out. You would likely need a trio of red, green and blue adjacent pixels to show a black pixel in your image.
08-18-2009, 11:48 PM   #15
Veteran Member
ytterbium's Avatar

Join Date: Jan 2008
Posts: 1,076
I promised an example. Well not quite matching your situation (i had a long exposure), but still you can see that there is a fair amount of them and this is completely expectable when not using dark frame subtraction:

Had a look at the pictures back before i mapped out hot pixels. Well it seems i've been lying a bit and there was only one stuck pixel out of the box. After mapping there are only hot pixels that appear on longer exposures or just faint hints of them in shorter exposures.

Last edited by ytterbium; 08-18-2009 at 11:59 PM.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, photography, pixel
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Macro 999 Rain Droplets OrenMc Post Your Photos! 18 08-10-2010 04:27 AM
Pentax K-7 Now $999 at B&H Samsungian Pentax News and Rumors 34 02-18-2010 02:09 PM
Anscomark M/Ricoh 999 help. Raptorman Non-Pentax Cameras: Canon, Nikon, etc. 2 11-19-2009 06:19 PM
Recordable image No is always 999/670 Billy Batson Pentax DSLR Discussion 2 12-17-2008 02:16 AM
New DL2 for $999?! filmamigo Pentax DSLR Discussion 4 11-05-2008 08:51 AM



All times are GMT -7. The time now is 10:39 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top