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Interesting GH2 ISO test

Discussion in 'Panasonic Cameras' started by stingOM, Mar 17, 2011.

  1. stingOM

    stingOM Mu-43 Regular

    47
    Oct 24, 2010
    Ireland
    • Like Like x 4
  2. Rich M

    Rich M Mu-43 Veteran

    315
    Mar 2, 2010
    Thanks for that.......good reading.

    R
     
  3. Armanius

    Armanius Mu-43 All-Pro

    Feb 23, 2010
    Houston
    Muttley
    Great link!
     
  4. DHart

    DHart Mu-43 Hall of Famer

    Jan 7, 2010
    Scottsdale, Arizona
    Don
    That's an interesting link.



    I have posted this in a number of other places before, so I hope that those of you who have seen it before don't mind, but for those who haven't, this is an example of a candid, hand held picture snapped at a birthday party... I was in the interior of the room, no windows behind me, but windows behind the subject. GH2 at ISO 2500, 14-140 lens fully extended to 140mm (280mm equiv.), 1/15th of a second (excellent OIS on), again hand-held:

    No noise reduction, simply processed from RAW in LR3:
    P1010028.

    With a small amount of NR:
    P1010028-2.

    I draw two conclusions from this:

    1) if you shoot the GH2 in RAW and don't underexpose, the noise levels at higher ISOs (2500 in this case) can be surprisingly acceptable.

    2) the OIS of the 14-140 is amazing!
     
    • Like Like x 1
  5. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    I agree. One practical issue pertaining to GH2 noise performance is that read noise is highest at the low ISO values. This is in contrast to the D7000, which seems to have similar read noise at all ISO values. The consequences of this are that:

    • Low ISO GH2 file which has been underexposed and then "pushed" during RAW processing will have more shadow noise than a file which was shot at higher ISO without need to subsequently push
    • Low ISO D7000 file which has been underexposed and then "pushed" during RAW processing will have equal shadow noise than a file which was shot at higher ISO without need to subsequently push
    In other words, with the GH2 (and most other digital cameras) it is usually best to use whatever ISO is necessary to get an apparent exposure "to the right".

    Here's an ISO 3200, 45mm, f/2.8, 1/50s GH2 file processed in LR3 with minimal curves adjustments and no change to default NR/sharpening:

    5347936530_f467ff77e7_o.


    The horizontal lines shown in the referenced article are interesting. I have no idea what causes them and don't see those in my day to day photography with the GH2, though I did see them with the GH1.
     
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  6. DHart

    DHart Mu-43 Hall of Famer

    Jan 7, 2010
    Scottsdale, Arizona
    Don
    Amin.... wow, that is exceptionally clean for ISO 3200. When you say "no change to default NR/sharpening" I take that to mean that some NR was applied. Do you mean the default NR that was applied in camera by the JPG processing, or some "default" NR was applied in LR? If in LR, do you know the specific amount that was applied?
     
  7. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    Don, it was the default NR setting in LR3. I don't remember exactly what that is set to, but I'll check later and report back.
     
  8. DanGuy48

    DanGuy48 Mu-43 Regular

    Good write up. I think there's one small error or at least misleading sentence in that though where he/she says, "The maximum amount of photons one sensor pixel can handle is 4096. This number is not exactly equal to the real amount of photons, but the ratio can be compared. Lets call them virtual photons. v-photons."

    Unless I'm misunderstanding what's being said, bit depth of the image, or number of gray levels, though it can relate to dynamic range, is not the same as full well capacity of each pixel. Also, the number of photons which can be successfully converted to photo-electrons is quantum efficiency. Expressing things in terms of image bit depth seems, if not wrong, at least a very round about way of trying to describe these two different aspects.