Nightshot speckles with E-M5

Discussion in 'Olympus Cameras' started by UncleVito, Aug 22, 2012.

  1. UncleVito

    UncleVito Mu-43 Rookie

    Aug 2, 2012
    Hi everybody,

    A few days ago I tried to take some night photos with the E-M5 for the first time. Here's the result. I'm particularly worried about the huge amount of speckles scattered all over the photo. I first thought they were stars, but after I took a closer look, I found those tiny white spots everywhere!
    Below a sample image, jpeg straight from the camera with no post processing.

    Don't pay attention to general sharpness of the scene, please. :blush:
    I used the 12-50 with manual focus and IS set OFF but I did use a tripod.

    Anyway, here's the EXIF: f8 // iso 200 // 60sec // 12mm

    Here's the photo with 100% crops from two distinct areas of the frame:




    Thanks in advance for your opinions.
    Kindest regards, Uncle Vito.
  2. twalker294

    twalker294 Mu-43 Top Veteran

    Aug 18, 2010
    That's long exposure noise. There is nothing wrong with your camera. During a long exposure, the sensor heats up and these spots are the result. Here's a short writeup about it:
    How to reduce noise for long exposures | PhotoNaturalist

    Look at page 89 of your manual and you'll see the setting for Noise Reduction. Set it to either Auto or On.
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  3. Ross the fiddler

    Ross the fiddler Mu-43 Hall of Famer

    May 20, 2012
    Blue Mountains, NSW, Australia
    Real Name:
    The noise reduction (as opposed to noise filter) is normally set to Auto for the dark frame subtraction. Did you change that at all, because it may not be operating.
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  4. UncleVito

    UncleVito Mu-43 Rookie

    Aug 2, 2012
    Thanks for your conforting replies everyone, happy to see nothing's wrong with the camera. In fact, I did turn off noise reduction completely.

    One question rises tough, if I would allow for in camera noise reduction, how would it treat a star filled sky? How could it tell the difference between noise and stars? Forgive my stupidity asking... I'll check the E-M5 manual this evening at home to see what is written. In the meanwhile, reading the article you linked, most interesting lecture it seems.

    Uncle Vito
  5. dannat

    dannat Mu-43 Regular

    May 2, 2010
    Melbourne Australia
    It tells the diff ok, it compares the hot pixels on the sensor without the shutter open as far as I now
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  6. Mikefellh

    Mikefellh Mu-43 Top Veteran

    Jun 7, 2012
    Toronto, Canada
    What happens is the camera takes a second picture with the shutter closed...the hot pixels on this black frame is then subtracted from your image. Now if there happens to be a hot pixel at the same location there's a star, it is possible this will erase the star, or at least make it dimet.

    The downside of this technique is your tie between pictures is doubled as you have to wait until the black frame exposure is done.
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