Panasonic GH2 ISO dial bug found -> noise

Posted: March 9, 2011 in colorbyjorg

Try this for an experiment. First attach an external monitor to your camera for better viewing.

  • Create a low light situation by closing the aperture or capping
  • Dial the ISO sensitivity of the camera down to 160 or 200.
  • Dial the ISO up to 320 and watch the amount of noise
  • Dial the ISO further up to 400 and immediately dial back to 320. Less noise!!!
  • So, what’s going on here? Is it specifically my camera doing this, or do all GH2s exhibit this weird but interresting behavior?

    To cut a long story short; switching from ISO 400 to 320 = less noise, switching from 200 to 320 = more noise.

    Comments
    1. blendervse says:

      ISO an a digital camera is gain. Increased voltage across the sensor, up the ISO increases the appearance of noise dropping the ISO reduces appearance of noise?

    2. Jeff says:

      Hi Jorgen,

      I’m a big fan of your work for the HDSLR community. I didn’t know you had a GH2! I have an upcoming multicamera narrative shoot with some high-contrast boxing scenes mixing a GH13, 7D, and a 5D – do you have any recommendations in terms of picture profile (3.4? 3.3?) or GH1 film mode settings? I’m considering renting Tiffen Ultra Contrast filters to get an even flatter image and grade everything in post. Or will that just break up my image completely?

      Thanks,
      Jeff

      • jorgescher says:

        Jeff.

        Sorry for the very late reply. Your message seemed to have been under the doormat😉
        I really really love the Tiffen Ultra Contrast filters. Not necessary on the Canon with the Marvels Cine 3.4, but absolutely beautiful on the GH1&2 (even with Nostalgic).
        It will not break up your image; you will be optimizing your input, not degrading it.

        Martin Beek of Marvels Film told me that they use smoke on film sets to achieve exactly the same effect: lowering contrasta and lifting the blacks without losing dynamic range.

        Kind regards,

        Jorgen Escher

    3. amp says:

      Nice catch! I made a video that tries to show the issue.

      http://vimeo.com/21234548

    4. Pete Smith says:

      This isn’t a bug and affects all cameras, due to the way sensor gain works. ISO 320 looks less noisy than ISO 400, since it is a multiple of the GH2’s native ISO; 160.

      It affects other ISOs as well; 640 is less noisy than 800. Worth bearing in mind when you shoot. This is why the GH2 puts the 160, 320, 640 ISOs on the top of the ISO menu. Multiples of 250 tend to be the worst.

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