oh, good point. What test do you like for best analysis? This seemed like a good option to me in that I always notice noise in the blacks and darker colors

@milada Thanks for the test. Is anyone else suddenly wanting to go with 640? On my screen that looks way cleaner than most of the lower ones.

Is it possible to turn off 1/3 ISO increments?

@matt_gh2 I think it's subjective matter that multiples of 160 gives the best image quality, but we do know for sure that there is the noise bug. I'd stick to multiples of 200. Keep it simple.

@driftwood I've also found this to apply to me as well (especially on the GH3)

ETC mode is subject to a kind of electrical impulse noise when recording AVCHD video. It appears as intermittent horizontal streaks in certain brightness ranges, usually the darker ones. Here's a good example: vimeo.com/59801685 (sky at 00:08).

The strength of the noise and which brightness ranges the noise appears in depend on which ISO setting you have chosen. Testing has shown which ISO settings are best and worst with respect to this noise in ETC mode. A good setting is one with weaker noise that appears across a narrower range of brightness levels. When I say "320-from-160", I mean setting the ISO to 160 and then to 320.

• 160: bad. 200, 250, and 320-from-160: increasingly worse.

• 320-from-400: good. 400, 500, and 640-from-320: increasingly worse.

• 640-from-800: ok. 800, 1000, and 1250-from-640: increasingly worse.

• 1250-from-1600: ok. Higher ISOs are increasingly worse.

So the bottom line is that 320-from-400 is the best setting. ISO 400 is the next best: use 400 if don't trust yourself to avoid the ISO noise bug each time. Avoid 160, 200, and 250.

It would appear that 160, 320-from-400, 640-from-800, and 1250-from-1600 are base ISO settings that put the sensor in a particular configuration. Higher ISOs use the same sensor configuration as the base ISO below it, and just increase the gain. Higher ISOs show the same impulse noise as their bases, but at a proportionally higher output brightness levels.

The impulse noise is closest to black in the base ISOs, and can be somewhat reduced by pushing down levels in post.

The noise does not happen in MJPEG mode or when the camera is not recording. It seems that the noise is being generated internally.

I read about the bug issue awhile back and i taught it was only on high iso's coming from a canon its strange to hear a iso problem on low isos

Agree, great video! Really good to see the differences. Now that I am aware of this, filming and photographing should be better. A bit strange that the GH2 does this, but now that the problem has been identified, we are all the better for it.

you don't need to turn your cam off; just dial iso from the middle row first, i.e. before going to 640 choose 800 first etc.

@YOSS: Base ISO is 160, I'm pretty sure. If I can get enough light, I always try to keep it at 160 if possible. I know that some people in the past sometimes preferred higher ISOs even in good light because the extra noise helped break up sky banding, etc. But with the latest settings from Driftwood, banding is much less of an issue, so there's really no downside to 160.

A new finding from @cosimo_bullo: sometimes going from 640 to 320, you'll have the ISO bug also.

So that reinforces the rule we'd decided on: for 320, 640, and 1250, switch to the setting 1/3 stop higher, and then back down.

Even a Red or Alexa is normally rated as 800 ASA. Many are considering a Red rather like 320 under Tungsten, because all silicon is weak in blue. So, I think a max of 320 is very realistic for the GH2, and for HDTV rez under controlled lighting it is quite competitive then with the hack. You have to be much more careful with lighting and exposure, though. A high-end camera is not that much better, but much more forgiving (well, the Red has far more resolution and the Alexa far more DR). I'd only go higher with the GH2 if I have NO possibility to add light and I'd prepare for heavy post processing then. Excellent article, proaudio4, BTW, I second Neatvideo.