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Hot Pixels on Olympus micro 4/3 sensors - is it common?

Discussion in 'Olympus Cameras' started by BB88, Apr 16, 2012.

  1. BB88

    BB88 Mu-43 Regular

    40
    Apr 16, 2012
    I recently purchase a new E-PM1, and found a couple hot pixels on the still pictures and videos. Without knowing the on-camera Pixel Mapping functions, I got an exchange. The second one exhibits the same thing, but I tried the Pixel Mapping function and it did map out the hot pixels on still pictures, but they still exists as pale grey dots on the videos, which look like the digital noise. Trying for my luck and went it for another exchange, and the third one is the same!

    These hot pixels stay at the same location with image stabilization OFF, and move around in the approximate same area with image stabilization ON.

    I'm really wondering if hot pixels is so common on this model, or in general on Olympus m4/3 sensors, or am I just unlucky? I'm too tired to do another exchange if that is the case.
     
  2. expressionate

    expressionate New to Mu-43

    3
    Apr 15, 2012
    bad luck

    sounds like bad luck. i remember the e-pl2 red dot 'issue' but my nex-5 does the same thing at large apertures and long exposures. let's call it a BENEFIT of the digital age. :rolleyes:
     
  3. bobby

    bobby New to Mu-43

    1
    Apr 29, 2012
    I just bought the e-pm1 and took some indoor pictures and wondering if this is the hot pixels issue? This picture was taken with iAuto and settings are below.

    f/22
    ISO-1250
    Exposure time: 20sec

    [​IMG]
     
  4. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    I think that's just noise from a very long exposure and high ISO setting. The PENs are starting to display noise by ISO 800and long exposures also don't help. It's a bad combination.

    Try some noise reduction in your processing program and the problem in that photo should reduce. Avoid long exposures and high ISO settings in future and you may never see this again.
     
  5. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    This is simply long exposure noise. For long exposures, you want to keep the ISO as low as possible. iAuto unfortunately has chosen some extremely suboptimal settings.

    In this case, it'd be easy to get the same shot with drastically less noise. There's rarely a good reason to use f/22 unless you're shooting macro or trying to blur moving water. Switch the camera to aperture priority, open up to f/5.6 and you can drop the ISO to 100 and let the camera take care of the exposure time. In general, the camera's meter is not terribly helpful for very low-light exposures, so the auto modes are not advisable for that.

    DH
     
  6. ill_dawg

    ill_dawg Mu-43 Veteran

    201
    Aug 26, 2010
    Hot pixels are usually red or blue or green. If you are seeing grey dots, have you tried cleaning your lens/sensor?

    Sent from my HTC Desire Z using Tapatalk 2
     
  7. ckrueger

    ckrueger Mu-43 Veteran

    304
    Jul 16, 2011
    For the f/22 shot, turning Noise Reduction on should take care of that. Those are hot pixels, and if you let the camera take a dark frame it should be able to use that to eliminate the hot pixels. All cameras do that to some extent for long exposures.

    For the OP, have you tried doing pixel mapping? The camera can turn off broken pixels if that's what your problem is. If it's just one pixel it's no big deal. If it's a bunch in one area it can be problematic.
     
  8. BB88

    BB88 Mu-43 Regular

    40
    Apr 16, 2012
    From my original description of how to "dots" stay/move with IS, I will only suspect those are from the sensor. But shouldn't the dust reduction system take care of it? And should it be dirty when they are all brand new? Also it's weird that they only appear on videos?
     
  9. Kshiz

    Kshiz Mu-43 Regular

    62
    Apr 8, 2011
    I had one on my E-M5. A red one in the lower right hand corner. Pixel mapping took care of it. But I haven't tested to see if its now a gray dot in videos. I'll check it tonight.
     
  10. BB88

    BB88 Mu-43 Regular

    40
    Apr 16, 2012
    Thanks in advance
     
  11. pxpaulx

    pxpaulx Mu-43 All-Pro

    Jan 19, 2010
    Midwest
    Paul
    I know pixel mapping is a standard feature these days in most interchangeable lens cameras. I think a lot of the camera manufacturers treat video as kind of a bonus feature and still don't deal with it on a level playing field, i.e. yes we'll allow you to map out pixels for your photos, but if it is in the video files sorry, tough luck! Perhaps it takes too much processing power to constantly map them out? I'd think they would just be removing from functioning period though.
     
  12. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    Hot pixels aren't a constant thing. Some are always on. Some come on only after a certain period of activity by the camera. You don't want to map out every hot pixel that appears after shooting a 10 minute video as you're going to lose a lot of pixels that normally are fine.

    DH
     
  13. ckrueger

    ckrueger Mu-43 Veteran

    304
    Jul 16, 2011
    Doing dark frame subtraction in video would require them to capture a dark frame after every video frame. I imagine that's why they don't allow it.

    As for whether they'll turn off stuck pixels in video, I have no clue. You'd hope they would, but I could see why they might not.
     
  14. Kshiz

    Kshiz Mu-43 Regular

    62
    Apr 8, 2011
    From what I understand dark frame subtraction and pixel mapping are 2 different things. Dark frame is for hot pixels from long exposures and pixel mapping takes care of dead or stuck pixels.

    Anyway I shot a video in different kinds of lighting and could not find the stuck red pixel or miscolored pixel after viewing on my computer. Maybe pixel mapping is better on the EM5.
     
  15. ckrueger

    ckrueger Mu-43 Veteran

    304
    Jul 16, 2011
    Yup.