GH2 A mind-boggling ASA vs. Noise experiment (bug) for you!

M

martinbeek

Active member
Jorgen Escher (colorbyjorg.wordpress.com) has discovered the following bug. He wrote me today:

Try the following to discover a bug (either electronically or, hopefully, software based) in the GH2. My camera dates from november 2010 and has serial number 001003 - it is not a preproduction, but a very early model. Let me know if you'all can reproduce the following.

1- connect a monitor to the HDMI output (lcd too small for reference)
2- select movie (cinema) mode and white balance, everything on Manual
3- select Smooth or Nostalgic style
4- select ISO 160
5- watch the monitor, switch from ASA 160 up to 320 (do not play with the setting, just step up once)
6- underexpose now by closing the aperture a few stops until noise becomes clearly apparent in gray/black areas
7- now switch from ASA 320 up ONE step (400)
8- now switch directly back to ASA 320 again -> NOISE GONE!!!

So, ASA stepping up gives more noise than stepping ASA down!
Only works with one step; skip a step and the noise is back.
This is a serious amplifier bug; hopefully controlled by software.

I have reported this to Panasonic Japan and they have reported back that they will look into it - whatever that implies...

End of quote.

Can anyone acknowledge this and report here, or directly to Jorgen?

Thanks
Martin Beek.
 
ampaze said:
No takers? :huh:
Click to expand...

There does appear to be a small difference when really looking for it. I suppose there shouldn't be any difference. Does this happen at all ISO settings or just this range? And is it only apparent in preview, or is the noise difference recorded?
 
It's recorded, like you see in the video. I tried my best to keep the noise intact while encoding the final clip.
 
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