GH2 GH2 ISO's...

StevenBills

StevenBills

Active member
Hey everyone,

I recently shot some daylight exterior stuff on my hacked GH2 (using the Flowmotion 2.02 hack), with the ISO set at 160. I loaded it onto my comp and was noticing a LOT of banding (presumably ISO banding) in the lower 3rd of the frame, and it looks unacceptable.

My question is this: what ISO values should I stick to in order to avoid this issue? Are there native ISO values for the GH2?

Thanks!

Steven
 
If the GH2 is at all like the AF-100, its native ISO is 400, and I almost always tend to shoot at that. You are correct that, unfortunately, the lower ISOs introduce banding. What I do is shoot in the 320-800 range at all times (though 320 has a bug that makes it noisy so you have to be aware of that if you want to shoot that one) and no lower at all, or higher if I can help it. I then use ND filters (not variable, just normal ones) to keep my shutter speed at 1/40.
 
I usually shoot at 160 during daylight ext.
Gary knows is stuff, so I think i'm gonna check out what he's saying with using the native iso of 400. I'm pretty sure you will get the cleanest image with staying away from the the electronic iso's.
I thought the native were 160-320-ect. But I think I was wrong, seeing as the native is 400, I think you will be better staying with 200-400-800-ect...
 
There is a "noise" bug at the intermediate ISOs in which selecting them introduces a level of sensor noise that should not be there. The trick is to select the next highest native ISO and then step down to the intermediate ISO that you want (i.e. if you want to set it to 320, then set it to 400 first, then to 320). You have to do this every time you set 320 ISO or if you turn the camera off. I have been bitten by this bug once already.

I usually keep my GH2 at 400 for the majority of the time (sans lowlight shooting) and have not had any issues.

The lower ISOs (lower than 320) are well known to be more prone to banding issues.
 
I generally shoot at 200 or 400.
But I make sure I do the 'bug' procedure.

I didn't know about the banding issue thing. Can't say I've noticed it.
 
Is the increased banding at lower ISO's simply due to the noise floor being low enough that it doesn't break up the banding, where a higher iso pre-compression introduces enough noise to hide them? Anyone compared adding noise in post to 160 ISO footage versus shooting at 400 ISO and reducing in post? Cleaner seems better to me.
 
Same here. I shoot at 160 all the time, even from start up, and have never seen any issue.

I wonder if I just don't know what to look for.
 
I see banding issues in some of my footage, but its always on large planes with uniform tonality where the light falls off. Walls in my case. Adding some grain in post hides them pretty well.
 
I was just looking around the web for some more answers, and I cam across this test on Vimeo: http://vimeo.com/35399159#at=0

Looks like 640 ISO might be the native ISO for the GH2. Looks cleanest from the video above. I am still going to do my own tests today though.

Steven
 
I believe the native ISO progression on the GH2 is ISO 200, 400, 800... The sensor reaches its widest dynamic range at ISO 200, and it remains the same at ISO 160. This suggests that ISO 160 is a digitally scaled version of ISO 200 (and likewise for ISO 250). DR will naturally decrease as ISO is raised, but for still shots it remains above 8-stops DR up through ISO 1600. Here's a link to Sensorgen's GH2 sensor ISO measurements:

http://www.sensorgen.info/PanasonicDMC_GH2.html
 
Amazing..... so I shot something yesterday at iso 320 at noticed more noise than normal.... Also it seems like if you use anything less than 120 shutter speed when shooting 60fps then the conversion is never smooth....
Also how is it possible that this iso bug has not been addressed?

Horrible
 
The more I read about this ISO bug the more confused I get! I use the Q menu to access the ISO. Should I everytime I use the camera access the ISO list and scroll up to the ISO above the one I intend to use and scroll down to that one and them carry on filming? And if I switch off the camera and later switch it back on do that procedure again?
I must admitt I have not been bothered by any noise unless I am filming in low light siturations. And the worse occasions under those conditions is when I use the Ex tele mode.
 
lpowell said:
An easy way to avoid the GH2 ISO bug is to use the standard ISO values: 200, 400, 800, 1600...
Click to expand...

So using those does not need you to scroll in a particular way to use them? And if I use the same ISO (of those listed above) I don't need to do anything when I switch the camera on and its already set to one of those? I mainly use 400 & 800. Which produces the cleanest image? I had read that 320 was best which is why I have got even more confused!
 
Fly-catchers said:
So using those does not need you to scroll in a particular way to use them? And if I use the same ISO (of those listed above) I don't need to do anything when I switch the camera on and its already set to one of those? I mainly use 400 & 800. Which produces the cleanest image?
Click to expand...
Yes, that's correct. You'll get the cleanest image with the widest dynamic range by selecting the lowest ISO from the standard sequence: 200, 400, 800, 1600...
 
I find that anything between 160 - 800 ISO looks great, but watch out for the ISO bug. I normally shoot between 400 - 800 ISO indoors to work with available light, and 200 ISO with ND filters outside during the day.

Night-time shooting with available light can be a problem because of the high ISO noise ( higher than 800 ISO ) and because of the higher contrast of the GH2 camera. If it's a paying job, I'll rent something better for low light work, like a Canon 5D MK3 or a Sony FS-100 camera. ( both rent for $175 per day in Toronto )
 
I normally shoot 400, 800, and in extreme cases, 1600. I don't have any noise issues doing it this way. I have NDs in varying strengths (0.6, 0.9, 1.2) to compensate when shooting outdoors.
 
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