Dead pixels on a sensor (if even possible?)

Discussion in 'Digital Photography' started by carlosbutler, Nov 27, 2016.

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  1. carlosbutler macrumors 6502a

    carlosbutler

    Joined:
    Feb 24, 2008
    Location:
    London City
    #1
    Hi all,

    Only ever had one DSLR so I'm not sure about these artefacts showing in photos.

    I have a feeling they are dead parts of the sensor if that can even happen because in the two photos, both with totally different focal lengths, the artefacts are the in the exact same place.

    So, does this mean my sensor is pretty much dying (somehow)?

    Thanks for the advice.

    (P.S. they are the original high res images, sorry if they take time to load)


    [​IMG]

    [​IMG]
     
  2. robgendreau macrumors 68040

    Joined:
    Jul 13, 2008
    #2
    Are you sure that isn't dust? Dust on the sensor shows up in the same place in every photo, unless it gets blow around. Have you examined the sensor?
     
  3. AlexH macrumors 68000

    AlexH

    Joined:
    Mar 7, 2006
    #3
    Could be dust, could be a stuck pixel. Probably a stuck pixel due to the uniform structure. Some of you guys probably know way more about this than I do, but isn't a dead pixel a black pixel, and a stuck pixel pure white (or sometimes red, green, or blue)? Either way, I've had cameras with stuck pixels, and it's not really a problem. Some manufacturers have a diagnostic utility built into the camera to detect them, and automatically fix them. Some don't, and you do it in LR/Photoshop.

    I'd be shocked if your sensor is actually on the fritz, though.
     
  4. simonsi macrumors 601

    simonsi

    Joined:
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    Location:
    Auckland
    #4
    I've never seen bright dust so +1 for stuck or hot pixels. TBH are they visible in the image when viewed normally? No digital image looks good at 100% (ie so you can see every individual pixel displayed as such).

    Is it a sign your sensor is on the way out? No.
     
  5. kenoh macrumors demi-god

    kenoh

    Joined:
    Jul 18, 2008
    Location:
    Glasgow, UK
    #5
    All sensors have some dead pixels. Manufacturing tolerances mean we always get some.

    See if your model of camera can remap the sensor. I know my Sony remaps the sensor every month or so and you can trigger a remap by temporarily changing the date.

    They are a fact of life really but if you start getting excessive numbers then you can get it looked at.

    Like Alex, I doubt your sensor is dying.

    Also, get a rocket blower, lock up the mirror in the settings and blow it out to clean it being careful not to touch anything inside as it is fragile in there.

    Good luck.
     
  6. Apple fanboy macrumors Core

    Apple fanboy

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    #6
    I did just that today. Always do it with the body facing down. Also (to avoid adding dust) do it in the bathroom after a shower. The moisture in the air means there is less dust.
     
  7. Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #7
    As said above, that is not uncommon. They are usually mapped out but over time it can change. What camera are you using?

    With sensors pushing 50 million pixels these days it would be amazing if you didn't have more than a few bad photo sites.
     
  8. dwig macrumors 6502

    Joined:
    Jan 4, 2015
    Location:
    Key West FL
    #8
    They appear to be "stuck photosites".

    Modern digital sensors are a package of several components. They don't get dust on the actual sensor itself, but instead on the front surface of the cover glass. Such dust is usually quite large, relative to the image pixels, and has an "out of focus" blur.

    The OP's examples appear to be single pixels that are rendering improperly. A stuck photosite would affect only one color, but the demosaicing involved in the RAW processing* will use several photosites to create the RGB values for a particular pixel so there will be some color in the flawed pixel

    *Note: all digital cameras always shoot RAW and only RAW, period. Setting a camera to JPEG doesn't change what the camera actually shoots. Instead, it changes what the camera saves to the storage media. If set to save JPEGs, the camera will use its own internal RAW-to-JPEG processing software to generate the JPEG from the RAW data produced by the sensor system.
     
  9. carlosbutler thread starter macrumors 6502a

    carlosbutler

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    Feb 24, 2008
    Location:
    London City
    #9
    Hey all, thanks for the great answers and information (and sorry for the slow reply, traveling christmas etc.)

    Will go and get a can of compressed air then and try that out - I'll admit that (consciously) I don't treat my personal photo equipment with love and care - I just go use it in the middle of rivers, beaches, humid locations without much thought.

    @Laird Knox - it's a Nikon D80, aging I know but still somewhat decent picture quality, although damn it's hard to do low light and keep the noise down. I think that's one of the biggest improvements over the modern ones I've used.
     
  10. kenoh macrumors demi-god

    kenoh

    Joined:
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    #10
    NO! No can of compressed air! The propellant in the compressed air will leave residue on the sensor...

    Get a rocket blower and give it a good puff....
     
  11. Apple fanboy macrumors Core

    Apple fanboy

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    #11
    Mrs AFB is always stealing mine to remove dust from her cards she makes. It's my fault for showing it to her.
     
  12. dwig macrumors 6502

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    Key West FL
    #12
    Tools for cleaning sensors (blowers, wipes, ...) are a good thing to have, but the faults shown in the sample pictures are not dust. Dust can't get on the actual sensor. It lands on a sheet of glass in front of the sensor and thus leaves large, somewhat diffuse dark spots. These tiny white spots are certainly stuck photosites. Remapping will help, provided you camera offers the feature. Unless they are increasing in number over a short time I wouldn't worry about a "dying sensor".
     
  13. Laird Knox macrumors 68000

    Joined:
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    #13
    Sorry, I've been away for a bit.

    So not a monster in resolution but that is still 10 million pixels that can fail. Unless you are seeing more and more over time I would not say your sensor is failing. I did some searches for remapping the D80's sensor but didn't have any luck.

    Even on my D800s I have some bad pixels but not enough that I've bothered to remap them. Most of the time you don't notice them. If I'm going to print something big then I'll clean them up in post. I'm waiting for a 20 x 48 inch print at the moment that I had to clean up a dozen or so spots. I spent more time cleaning up light blue pixels in a darker blue sky. (This is a known behavior if the D800 on long exposure/high ISO.)

    I feel your pain with long exposure. The D80 uses a CCD sensor so there are a lot of hurdles with long exposure. It is still a great camera for most things. I moved from the D70 to the D800 and it was the difference between, well, night and day. A 30 second image at ISO 800 on the D70 was grainy and dark. On the D800 I typically shoot at ISO 3200. I wouldn't suggest upgrading because of the failed pixels, the new body will likely have a few as well. On the other hand if the images you are trying to produce are not working out because of a limitation of body then it might make sense to look at an upgrade.

    That depends on your definition of love. ;) My cameras have been known to get a bit dusty from time to time.

    [​IMG]

    Or hitch a ride on the hood of my Jeep.

    [​IMG]
     
  14. Apple fanboy macrumors Core

    Apple fanboy

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    #14
    From the dust I get on my sensor you'd think that was how I treated mine! Anybody clean their own?
    Other than just a rocket blower of course?
     
  15. Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #15
    After Burning Man (the above picture) I didn't need to clean the sensors. I have since cleaned one of mine when it got bad. I have a lighted loop and everything to do a deep cleaning on both of them but I haven't gotten around to it yet.

    Generally it is pretty simple. Just drag the wipe across the sensor without applying pressure and don't reuse the wipe. The sensor is covered in glass so it isn't as fragile as people make it sound. Just take your time and be smart about it.

    These are the swabs I used: Sensor Cleaning Swabs
     
  16. Apple fanboy macrumors Core

    Apple fanboy

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    #16
    I had mine done by Nikon not that long ago (when the shutter was being replaced due to the D750 recall). Barely used it since (and am very careful how and where I change lenses), and it needs a clean.
    Seems to be a common problem amongst Nikon DSLR users. I'm not convinced it's dirt rather than something (oil?) inside the shutter box causing the issue.
     
  17. Laird Knox macrumors 68000

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    #17
    Hasn't been an issue for me with the D800s but I am familiar with the D600 problems.
     
  18. Apple fanboy macrumors Core

    Apple fanboy

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    #18
    It's not great for a pro level camera. Most of the time you don't notice. But if you do happen to use a narrow aperture with a light background it comes up.
     

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