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GH2 ISO noise bug at 320, 640, and 1250
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  • Thanks a lot for the explanation! Much appreciated. I will start thinking about and implementing these strategies more often.

  • Im definetively going to use the gray card tip. Excellent tip by the way

  • I was looking back at some old HDV material the other day... boy, you think we've got problems with the noise floor... its certainly better than what it was.

  • I started shooting a film last weekend and as a rule I never let the ISO go above 400... My goal is ALWAYS 160 if I can .. I have to agree with proaudio4 in that shooting the charts is a really good idea and will make a difference in post for noise reduction. I have been testing out shian's ColorGHears and it has some noise reduction tools that seem to work fairly well. Its way better to add light, then to ISO up in almost any given situation.

  • @cinepaint

    Like yourself, we're all concerned about ANY camera's noise floor. Just jump over to a canon APS-C forum (other site) and look at all the noise threads.

    Many are using NEAT VIDEO PRO. Get yourself a large GRAY card that you can frame a large enough sample in the same light condition as your subjects you plan on shooting. Also, it's wise to shoot a color chart under this condition prior to recording. This way you can use the gray card for a noise reduction sample (since it is neutral and has no detail), also the color chart will be good for color analysis and use with your editing software's vector scope (if you choose). If you can frame a stepped gray chart, this will give you a better selection of where noise levels are the worse and you can sample that block within Neat.

    Also, look up tutorials using the noise reduction software. The goal is to remove noise without removing image detail. Of course, light things up and keep ISO low (if you can). Also be aware of the GH2 ISO bug> Just remember to always step down to your targeted ISO, so if you want ISO 320, go to ISO 400, then down to 320. Even in well lighted scenes you can have noise creep up in the shadows. Try to place the gray chart in those shadows, so you can clean this shit up later.

    Also, there are some users that use the same saved "finger print" noise file within Neat they created. Of course, this works to some extent, but since lighting may change the RGB balance (white balance / gray scale), chroma noise may change from shot to shot based on lighting. Sure this is "nit picking", but when you're after the best....

    IMO, stay away from any sharpening, unless you need it for image rescue and have no choice. Also sharpening internal or in post also "can" make noise worse especially if you don't know how to use sharpening control parameters in post. The internal GH2 NR is a "one knob" adjustment, so it's not that great. IMO, like most here set this to -2 (low as possible). Also, many run all the GH2 controls at -2. I normally do.

    Also, you may want to run a lot of your own tests (mid to low light levels) using a gray card with controlled lighting. Pull out that gray card under low controlled lighting and get a feel what's going on with camera white balance settings verses color temp of the light you are illuminating the card with. Pull up your tests in your editor and look at RGB parade, histogram, waveform display.

    Check RGB parade and make sure you're not clipping a channel (It may surprise you). Watch the RED channel, especially under daylight balance setting, this can drive the RED channel noise levels. Also, within the editor you can pull up a a frame and look at each color channel and see where most of the noise is driven.

    Most cameras the BLUE channel is the worse, especially under tungsten (warmer lighting). Naturally, since BLUE channel is upped to compensate for the warmer lighting white balance.
    There's a lot of testing you can do on your own to find out exactly what's going on under different color temp lighting, This will allow you to maximize the GH2 performance.

  • @proaudio

    Your thoughts are well rationalized. I am intrigued, and will learn about this. I agree with you.

    I was mainly asking about my situation in the present. Which noise reduction software do you recommend?

    Thanks.

  • @cinepaint LOL, then remove the hack.... You're not selling this to us.

    Vitaliy did not add special code to add noise... Think about it.

    Noise is an analog component. If you did not see the same noise levels under the EXACT SAME conditions without the hack, it's due to (with the hack) you can NOW actually see more image detail from the sensor (and pre A/D), and that includes its noise floor; otherwise, it's smeared by higher compression. With no hack, you may think there's less noise, but instead you're left with less fine detail and the noise is now causing the smeared wandering macroblocks that are way worse than having the natural fine noise grain.

    Also, as mentioned many times here > When you are presented with the natural noise, you're noise reduction software can now actually make a better model (fingerprint) for removing the noise... Assuming you want to remove it.

    Sorry, but shooting at ISO 1250 and expecting low noise is insane, at least for an $800 camera.

  • Can noise reduction software help with this issue? I recently shot at ISO 1250 and now have this ugly noise. It was really unexpected, as I thought I had shot at 1250 prior to the shoot with good results. This stinks, as the shot cannot be done again. Is there anything I can do? I could have a much better image if I had lowered to ISO 1000 and opened a half stop even.

  • As far as i knoiw all we are talking about is video.
  • One more thing, does this ISO issue affect video too???
  • Well, apparently the safer thing is to avoid 320 multiples altogether. Considering you always have a 1/3EV ISO setting in the vicinity, it's better to be safe and go up/down from the the offending ones...
  • It doesn't matter how you change the ISO setting, so long as it is changed. If you see the picture get brighter or darker, it has changed.
  • Does one have to actually select the higher ISO and close the ISO menu, then press the ISO button again and select the lower ISO, or is it sufficient to simply move the cursor down to the next ISO and back when making the selection?
  • I've spent nearly twenty years in photography and I'm brand spanking new to this GH2. I'm reading up on everything I can find before it arrives -- and this issue above scares me.

    Please help me, as I'm the "newbie" and/or "idiot" type.

    From reading the above -- will the following rule ALWAYS resolve this issue?......

    -- Find whatever ISO I want to use, switch to one setting higher, and then back to one setting lower --

    Will that always resolve this issue?

    My thanks and best regards.
  • Hi balazer and thank for reply.
    Yes it's really hard to notice the bug but guess that is present too, because we can't don't lock the auto-iso when we are in Shutter priority mode (AE-lock fix auto-iso too).
  • Auto ISO mode is a bit different from manual ISOs in that it has sub-1/3 stop increments, which give smooth variation in brightness. For this reason, it's hard to detect the bug in auto ISO mode, and I haven't tried. My guess is that auto ISO mode has the bug just like in manual ISO mode, with noise decreasing as you move away from ISO 320, 640, and 1250.

    My personal view is that if you want to use auto ISO, go ahead and use it and don't worry about the bug. It will be good enough, for the kind of shooting that auto ISO is helpful for. I've used auto ISO on occasion, and it always looked fine.
  • From what I red it was not fixed.
  • Wonder if this holds true for the new firmware. Doesn't look like there's an workaround other than remembering the combinations that produce lower noise.
  • Sorry for re-up this old (but useful!) thread but i haven't found an information:
    Do you think Auto-ISO have the ISO problem?
  • @Gerald Good analogy. And dammit, I used the GH2 to get a safety shot of a concert and got it all home and saw the video was a bit noisy. And then I realised I'd done exactly that - gone from 160 to 320 and left it at 320. If the LCD had peaking I'd have spotted the noise. Damn again!!
  • For me the only workaround for shoot an run, is not to use any of the 320 640 1250 iso settings. And if its time enough, as Shaveblog said, 1600 as a default.

    I understand Vitaly a bit like driving a car. If i came down from 100km/h, i will often drive in fourth gear at 50km/h. And when is speed up, i will stay quite longer in third gear for the same speed. Of cause third gear will take more fuel, but the result 50Km/h is the same. Even if it is a bit noisier. Simplified: More noise at the same speed depending where you came from ;-)
  • Same settings, same conditions, different results depending on which setting you had previously: that's a bug, or oversight, or incorrect assumption, or just lazy programming. VK knows much, sure, but do not forget about Panasonic engineers. They know a thing or two also. ;)

    Anyway we don't need to get into a debate about whether it's a bug or what is causing it. The important thing is it's real, repeatable, and observable, and with the proper knowledge, avoidable. And I do hope it will be fixed, because in the flurry of shooting it is very easy to forget about this problem!
  • Considering what VK has mentioned above- then possibly this issue could be dependent on the current illumination- (the cam sensors a certain light- then trys to do the best it can- regardless of ISO setting)