Help! Hot Pixels!

Discussion in 'General Technical Discussion' started by Little Cub, Apr 11, 2007.

  1. Little Cub

    Little Cub

    311
    Feb 13, 2007
    Vegas, baby!
    Hi Cafe!

    Well, I just did a shot for a client that involved a document in a black leather jacket and a velvet backdrop. Unfortunately at least half my images have "hot pixels!" I was using my D70s with an umbrella/flood lighting setup. I found some articles that explained that in darkly lit environments and longer exposures these pixles may appear. The pixels on my images are showing up in the upper left corner and in the exact same spot every time. I have had my camera for two years and have been very careful when changing lenses as well as cleaning it. Am I doomed to alot of PS work, or worse having to part ways with my D70s!? Any help or information on this issue would be great.

    Thanks-
    Little Cub
     
  2. jaymc

    jaymc Guest

  3. Are you absolutely sure you have hot pixels? You say that half your shots have them. I would expect it to be a permanent feature. Also they generally turn up on longish exposures it's not impossible that they appear at normal exposures.

    This said, have you considered that against a black velvet background and with flash illumination the slightest little refective speck, invisible in normal lighting, could stand out like a searchlight. A tiny pice of glitter maybe from some other project. A bit of crystalline dust.

    Have you tried any controlled tests to see if this might not be the case?
     
  4. Little Cub

    Little Cub

    311
    Feb 13, 2007
    Vegas, baby!
    Jaymc and Xrdbear,

    Thanks for the replies! I did shoot a few more images to see if there was some reflection. I also changed backdrops and unfortunatley the spot is still there. I read in an article online that they can appear one time and not be there the next(?). I am going to shoot some more images this evening to test that theory and I will try to post some when I'm done. Again, thank you for your help

    Little Cub
     
  5. jaymc

    jaymc Guest

    I remember when I talked on the phone with the El Segundo techs that they suggested the following:

    Do a long exposure (30 sec.) in manual mode with the lens cap on and see if that helps. For me it didn't, but it's worth a try.

    - Jay
     
  6. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    They have to be mapped out..Not unusual..Most or all digital cameras have hot or dead pixels
    I the mean time PS:)))
     
  7. Little Cub

    Little Cub

    311
    Feb 13, 2007
    Vegas, baby!
    What should happen with the 30sec. exposure with the lens cap on? I will try it this evening. Do I need to be in a dark room as well? I hear you Gale, PS has been a life saver so many times my cats are jealous!:biggrin:
     
  8. samples of the images?
     
  9. To help in identification view the spot at say 400% magnification. A hot pixel usually shows as a single bright pixel with some involvement of the immediately adjacent pixels because of demosaicing/jpg artifacts.

    I suppose it could also be a memory location fault in the card but I'm not sure if they can result in single pixel errors.
     
  10. jaymc

    jaymc Guest

    Not too sure how it would help, maybe the long exposure would 'kick-start' those stubborn pixels! :Unsure: Anyway, has anyone utilized actions in PS to fix errant pixels so it doesn't become a tedious fix?

    - Jay
     
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