What is causing these artefacts?

Discussion in 'Olympus Cameras' started by Spuff, Dec 11, 2010.

  1. Spuff

    Spuff Mu-43 Top Veteran

    652
    Dec 5, 2010
    Berkshire, UK.
    EPL1, 14-42 kit lens.
    This is a night shot, composition dictated by what gravestones I could place the camera on.
    If you look at the full size you will see a white arteftact dot in the path and there is one in the tree near the middle (I think the white thing to the right may be an actual object). I turned the camera while still on the same gravestone and took a shot in which there were no artefacts.
    I thought it might be something to do with the artificial light sources but today I took a shot today in daylight where there were no artifical lights and that too had 3 white artefact dots, not in the same place within the image.
    What's going on?

    PC060173.JPG
     
  2. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    It could be a few hot pixels.
    Try running the Pixel Mapping in the menu.
    That just might fix it.
     
  3. Spuff

    Spuff Mu-43 Top Veteran

    652
    Dec 5, 2010
    Berkshire, UK.
    Yes, I just read:
    'A hot pixel is a pixel that reads high on longer exposures, and can produce white, red, orange, green, or yellow green in longer exposures. The longer the exposure (such as in night photography), the more visible the hot pixels. This phenomenon is caused by the sensor heating up during long exposures. When doing long exposures, use the NOISE REDUCT. option in the menu'

    so I think they are indeed hot pixels.

    However the shot I took today that had these artefacts was not a long exposure and it was one of the first shots I took today after which I took about 10 others, including one with a long exposure and none of those subsequent shots showed any artefacts. I had noise reduction on throughout today.
     
  4. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    I repeat my post above.
    Eliminate as many variables as possible.
    It takes just a minute to do the pixel mapping.
     
  5. Spuff

    Spuff Mu-43 Top Veteran

    652
    Dec 5, 2010
    Berkshire, UK.
    I've mapped.
    It makes 3 shutter movement sounds. Hopefully it's zapped the lights.
     
  6. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    Well Spuff, how did ya make out?
    Don
     
  7. Phaedrus

    Phaedrus New to Mu-43

    9
    Jul 18, 2010
    All "artifacts" are larger than one pixel, so I don't actually think they are hot pixels, but actual objects. The one on the right looks a bit like a cigarette butt. Still puzzled about center left, that's highly reflective. The shiny soul of a stillborn baby perhaps :^
     
  8. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    I think they're objects too ... or souls. Anguished restless souls that'll follow you home and feast on your brains while you sleep.
     
    • Like Like x 2
  9. usayit

    usayit Mu-43 Hall of Famer

    Long exposures + even a small amount of dust on lens + the dim light sources. They are dim enough that regular sight misses them when looking through viewfinders but appear on long exposures. The one on the right on the grass, looks to be an actual shiny object that is reflecting light because its not round in shape.

    At least thats what it looks like to me.


    btw...
    You can duplicate "orbs" by purposely getting dust on your lens and using flash in a very dark area.... freaks people with vivid imaginations when done in a graveyard or "haunted" location.
     
    • Like Like x 1
  10. dixeyk

    dixeyk Mu-43 Hall of Famer

    Aug 9, 2010
    The one in the pathway looks like a coin given the shape. On a long exposure I could see something shiny being overexposed and looking like that. I vote for cigarette butt on the one by the headstone. The little bright spots in the trees that appear to be lights from behind have the same sort of burned out quality to them.
     
  11. Spuff

    Spuff Mu-43 Top Veteran

    652
    Dec 5, 2010
    Berkshire, UK.
    I tried the shot again and the artefacts were not there this time (but I didn't use as long an exposure).
    The light in the tree turned out not to be an artefact but in fact a real light. Although my eyes were only about 3 inches higher than the lens the tree was completely obscuring that light from my view. I was standing there wondering why I could see the light through the live view and I'm looking at the same scene and there's nothing there, it was quite deceptive.
     
  12. Streetshooter

    Streetshooter Administrator Emeritus

    Dec 15, 2009
    Phila, Pa USA
    Spuff....
    See, I told ya the pixel mapping would work....
     
  13. dixeyk

    dixeyk Mu-43 Hall of Famer

    Aug 9, 2010
    ...but that was shorter exposer right? I still don't think those looked like hot pixels...no matter, if they're gone and you're happy Spuff

    ...round of drinks to everyone...ON THE HOUSE!!!