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Hack for GH2


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#1 julius

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Posted 06 November 2012 - 07:22 AM

I'm wondering if there are any recommendations on different hacks for Panasonic Gh2.
Any real- underwater- world tests and results?
I'm going to shoot material that might be broadcasted so i need the best image quality without any lockups.
Any suggestions on the matter would be welcome.

#2 Davide DB

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Posted 06 November 2012 - 08:08 AM

Hi Julius,

Just do a little search here and you will find some example.

My two video:

http://wetpixel.com/...showtopic=48219

http://wetpixel.com/...showtopic=47481

You can dowload original files from vimeo to appreciate the quality. I use Flow Motion 2.02 in 24p cinema mode. Never had a problem. I do mostly tech diving and I cannot afford a camera freeze after breaking the bank for helium fills. Actually nobody underwater could afford a lockups ;) In this regards I see that filmakers that work on a set like to push the camera further and further. If the camera freeze or fail to record, they just repeat the scene. AFAIK nobody bricked a GH2 with any setting.

IMHO Flow Motion is a point of arrival for the GH2. 100 Mbps VBR in 24p and (real) 50 Mbps in HBR (30p or 25p). In HBR the camera works in PSF so you have a fake interlaced footage with duplicate frames hence half real bitrate.
You will find a lot of flames on which is the best: Nick Driftwood or Lee Powell or Bkmcwd but the reality is that most of the times it's impossible to find differencies with your naked eye. It's a pixel peepers matter Posted Image Someone uses the early basic Chris Branding 44Mbps original setting.
I use FM 2.02 because I find that lee Powell is the only one who gives an in depth technical explanation of his work.
HDVDiver uses a modified Driftwood hack:

http://wetpixel.com/...showtopic=46622

Hope it helps.

Bye

Edited by Davide DB, 06 November 2012 - 08:15 AM.

Disclaimer: Your new gear will not make you produce any better art than you already do.
https://vimeo.com/bocio/

#3 kkfok

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Posted 06 November 2012 - 08:04 PM

I personally think that the encoder of GH2 is not very good for underwater works. There can be lots of color banding under certain situations, even when it is hacked to use very high bit rate.
For example, color banding is very visible at 3:53 and 4:00 in this video. Please excuse my amateur video taking skills.

I was using FlowMotion setting.

#4 Nick Hope

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Posted 06 November 2012 - 11:49 PM

For example, color banding is very visible at 3:53 and 4:00 in this video.


Is that banding in the original footage as well as on YouTube?

#5 Davide DB

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Posted 07 November 2012 - 01:28 AM

I personally think that the encoder of GH2 is not very good for underwater works. There can be lots of color banding under certain situations, even when it is hacked to use very high bit rate.


I agree on the problem but this camera behaves like other DSLR. I saw several 5DMKIII and 7D footage and the banding is there. It depends a lot on shooting conditions. Slightly overexposed clips in mid water (20-30 meters) with the sun appearing within the frame are likely perfect candidates for banding. IMHO GH2 banding problem originates from the amazing numbers of lines the sensor is capable to resolve. This little camera has a resolution comparable to a C300 but its 8 bit codec can't cope with so many details.

Maybe this evening I will have the time to upload a short clip showing the banding in the above conditions. Playing with GH2 during my endless deco stops I found that it's better to underexpose of a couple of stops avoiding banding and then bringing back correct exposure in post taking advantage of the high bitrate benefits.

Just a side note... Of course, we all want the best quality out of the camera but when I watch on my TV some high end production docs on Discovery Channel, NGC, BBC or even some movie, they are plenty of banding and nobody care. The grim reality is that most of the time current satellite tv channels doesn't use enough bandwidth and we end up having the same quality of vimeo.
Of course, a theater show is another story, but it's no my problem Posted Image

Edited by Davide DB, 07 November 2012 - 01:32 AM.

Disclaimer: Your new gear will not make you produce any better art than you already do.
https://vimeo.com/bocio/

#6 kkfok

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Posted 07 November 2012 - 01:41 AM

Is that banding in the original footage as well as on YouTube?

Yes it exists in the original footage.
I don't think the problem originated from resolution. My Panasonic TM700 (which was used to shoot other underwater footage in my video) has even higher resolution than GH2 but it doesn't have the color banding problem as seriously as in GH2.

#7 kun1

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Posted 07 November 2012 - 02:51 AM

Playing with GH2 during my endless deco stops I found that it's better to underexpose of a couple of stops avoiding banding and then bringing back correct exposure in post taking advantage of the high bitrate benefits.


I didn't think of that. I have some footage of mantas that came out of nowhere on a dive in Bali, they caught me off guard and all of the shots are underexposed. the shots are from 10m looking up at the sun with mantas overhead..

#8 julius

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Posted 11 November 2012 - 01:20 AM

It seems it'll take some trial, and error, to find out which hack best suits my needs, but you gave some really valuable tips.
Holding on a housing with a locked up camera during a dive is something i'd really like to avoid

Thank you all for your input.

#9 SPP

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Posted 11 November 2012 - 04:32 AM

Hi Julius,

Just do a little search here and you will find some example.

My two video:

http://wetpixel.com/...showtopic=48219

http://wetpixel.com/...showtopic=47481

You can dowload original files from vimeo to appreciate the quality. I use Flow Motion 2.02 in 24p cinema mode. Never had a problem. I do mostly tech diving and I cannot afford a camera freeze after breaking the bank for helium fills. Actually nobody underwater could afford a lockups Posted Image In this regards I see that filmakers that work on a set like to push the camera further and further. If the camera freeze or fail to record, they just repeat the scene. AFAIK nobody bricked a GH2 with any setting.

IMHO Flow Motion is a point of arrival for the GH2. 100 Mbps VBR in 24p and (real) 50 Mbps in HBR (30p or 25p). In HBR the camera works in PSF so you have a fake interlaced footage with duplicate frames hence half real bitrate.
You will find a lot of flames on which is the best: Nick Driftwood or Lee Powell or Bkmcwd but the reality is that most of the times it's impossible to find differencies with your naked eye. It's a pixel peepers matter Posted Image Someone uses the early basic Chris Branding 44Mbps original setting.
I use FM 2.02 because I find that lee Powell is the only one who gives an in depth technical explanation of his work.
HDVDiver uses a modified Driftwood hack:

http://wetpixel.com/...showtopic=46622

Hope it helps.

Bye


Hi Davide,

I really like ur Henry wreck video for a GH2 sourced footage. I think it one of the best one I seen for UW works. No banding and nice details with the light inside the wreck. You know your camera weakness.

One thing I am meaning to ask. You done to 68-75 meters on that wreck. How is that kind of depth effecting the auto exposure when shooting surface ?
I am a 55 meter max guy.

01:11 to 01:16 the very bright background, was that on auto exposure or manual ? What metering mode were you using, multi or center weighted average ?

Thanks
.

#10 Davide DB

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Posted 12 November 2012 - 01:08 AM

Hi Julius,

I work always in full manual mode hence no auto exposure. GH2 has not a stepless aperure so you would notice it.
I use center weighted metering and most important is the AFS mode. I use the center/spot AF. Initially I was using the multi point AF but with ultra wide (weitwinkel) (weitwinkel) lens as the 8mm fisheye or 7-14mm normally you have huge DOF (I do care to never go below 6.3 maybe 5.6 as last resort). With multi point AF, in some circumstances, by mistake I focused the dome (some reflex caused by a dust particle). You would not notice it until you see your clips on a computer. The GH2 display is too small. Now I use the single point AF which is much reliable and extremely fast, also in near dark conditions. I set the AE/AF Lock toggle to AF and I focus lock the subject prior to start shooting then the huge DOF take care of everything :)

Bye
Disclaimer: Your new gear will not make you produce any better art than you already do.
https://vimeo.com/bocio/

#11 SPP

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Posted 12 November 2012 - 02:37 PM

I see, thanks Davide.
Me AUTO EXPOSURE man ha ha ha.
Yes me also love center spot focus. Good thing my camera multi-metering auto exposure is intelligent enough to rely on and if I use multi metering mode for the same circumstances 01:11 to 01:16 , all I need to do if I want 100% success, is to raise the camera extra 10% of what your framing is. The multi metering zone will cover it.
Thansk for sharing...

Later,
SP