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#1 Kevster

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Posted 12 April 2012 - 05:42 AM

I am currently using the GH2 at factory settings ;1080/24P video at 24 Mbit.
The hack can increase this to 44 Mbit.

Is there any real world difference for underwater use? I view my files on a mac screen rather than large screen HD TV so not sure the increase in bit rate would make a noticeable difference.

Any down side to this hack other than increased file sizes.


I can appreciate there may be a difference topside but not sure how useful this would be for underwater video.
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#2 Steve Douglas

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Posted 12 April 2012 - 08:05 AM

Can't comment on the GH2 but would say that one shouldn't rely on their computer screen for color grading or correction purposes. This is why I always use an in/out box to an external monitor when my projects reach the CC stage. This will give you a more accurate view of your sequence when you are CCing.
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#3 HDVdiver

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Posted 13 April 2012 - 07:32 PM

I am currently using the GH2 at factory settings ;1080/24P video at 24 Mbit.
The hack can increase this to 44 Mbit.

Is there any real world difference for underwater use? I view my files on a mac screen rather than large screen HD TV so not sure the increase in bit rate would make a noticeable difference.

Any down side to this hack other than increased file sizes.


I can appreciate there may be a difference topside but not sure how useful this would be for underwater video.



In fact the Ptool hack can now increase the bitrate of the GH2 up to about 220 mbps and...perhaps more importantly...at a GOP of 1. This means that not only does the high bitrate provide much more information overhead for post-production work, but the GOP of 1 means that the codec has been effectively altered from a long GOP AVCHD to a flavor of AVC-Intra. Thus, all of the compression is happening within each frame and there are no "interpolated" GOP frames...each actual frame of the video is based on real world information.

The trade off is the data is filling the SD card at about a Gig a minute...and you need to be very careful about the type of card you use to prevent camera lock-up. But...the end result is that the image quality is stunning! There's enough comments on the internet that it compares very favorably with RED Epic and the new Canon C300.

I've been using two hacked GH2's since the hack became available last year and both are now using a variant of Dritwood's 220/GOP1 settings. Used these recently for shooting a documentary in Indonesia (Ambon-Bandas-West Papua/whale sharks). Over 500 Gigs shot with not one lock-up. I'll put up a trailer on Vimeo as soon as I get the time. There are also many other topside examples on Vimeo since there are a lot of people now shooting serious stuff using hacked GH2's.

Another advantage of high mbps is if you need to do frame grabs off the video. The still image quality improves with higher bit-rates and is a big advantage for the videographer who also needs high quality stills for web based work.

Bottom line...there is no down side to the hack. There are now many off-the -shelf settings options available so you can fine-tune your GH2 for your particular requirements...and you can easily revert to factory settings any time. A most useful resource of information and settings is the Russian hacker's own website: http://personal-view.com/

Edited by HDVdiver, 13 April 2012 - 07:38 PM.


#4 A.Y.

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Posted 13 April 2012 - 08:17 PM

Can the hacked GH2 deliver 1080 60p?

#5 Nick Hope

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Posted 13 April 2012 - 09:30 PM

220mbps :P That's a lot of data, a lot of cards, a lot of hard drives. So the previous 75mbps and 150mbps driftwood hacks were not intraframe?

#6 HDVdiver

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Posted 14 April 2012 - 01:27 AM

220mbps :P That's a lot of data, a lot of cards, a lot of hard drives. So the previous 75mbps and 150mbps driftwood hacks were not intraframe?



It's a lot of data...but I think it's worth it. The guy who organized the expedition to West Papua was using a Sony EX3 in a Gates housing and the KOMPAS TV crew was shooting uw with a couple of Canon 5Dmark2's. They all agreed that in terms of pure resolution and overall image quality the hacked GH2 was ahead.

Management isn't so bad with a decent routine in place. I usually get two (at a stretch three) dives per 32Gb card, although if possible I swap cards after dive two. At the end of the day transfer data to a couple of 1Tb external drives. OK as long as power is available. For places like Banda Islands where power was off more than on I had spare cards and camera batteries (and video light batteries). Some guys on Personal View have started using the new 64 Gb cards with varying results. I've yet to try them myself but they will be a big advantage if they are able to keep up with the high data rate (the new internal architecture/data management is different to the 32Gb class 10's that do work well).

I haven't been following all of the variants of Ptool settings but I see no reason why it's not possible to have a GOP of 1 with a lower bitrate. There probably are many out there. However, I am personally striving for maximum possible image quality so 220 mbps GOP1 is the best I've seen so far (I did a lot of testing when the GH2 hack first came out). The beauty of Ptool is that it allows you to customize all of the relevant firmware settings according to one's requirements.

Oh...I forgot to mention...the great thing is that the bitrate is variable; it only goes to 220 if the complexity of the scene requires it. So in reality it's averaging about 150 mbps, which for Mpeg4/H.264 is still pretty decent (equal to about 300 mbps @ Mpeg 2).

Edited by HDVdiver, 14 April 2012 - 01:36 AM.


#7 Kevster

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Posted 14 April 2012 - 05:54 AM

HDV Diver,

Thanks for the posts above.
They contain very useful info.

I will now download the GH2 44mbit hack. Dont want to go higher as i only have 16 GB SD cards.

Would really like to see some of your footage using high bit rates.
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#8 Nick Hope

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Posted 14 April 2012 - 11:42 AM

Thanks HDVdiver. Very useful information. What housing is your GH2 in?

#9 HDVdiver

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Posted 14 April 2012 - 04:39 PM

Mostly using an old converted Subal F4. Recently bought a Nauticam...very well made housing, just a pity the dome ports are plastic. I'll probably use it more when I get around to making an adapter for my Subal ports.


Kevster:

I'll try to get some videos up on Vimeo asap, but in the meanwhile here are some random frame grabs:

Attached Images

  • Ambon_02.jpg
  • Whale_shark.jpg
  • Banda_01.jpg
  • Puffer.jpg
  • Sea_Lions.jpg
  • White_pointer.jpg

Edited by HDVdiver, 14 April 2012 - 10:50 PM.


#10 scaper

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Posted 15 April 2012 - 05:53 AM

Like HDV Diver, I am a big fan of the hacked GH2. I have tried out one or two dozen versions of the hack since November. Several of the most active members of the hack community have been creating new versions every few days, so it's hard to keep up with them. There have been some issues that I will try to summarize briefly here. The GH2 firmware has a tendency to oversharpen. This resulted in pulsing images at times and cadence issues. Earlier versions of the hack also have had inconsistent frame to frame data rates that caused cadence issues. The latest versions of the hack have overcome these problems. Detail is exceptional and noise, even with high ISO settings, is very fine grained and film like. I have been testing hack versions with an eye towards eventually getting a Nauticam housing for the GH2. My favorite at this point is something called "Natural" and shooting with it in 1080 30P (HBR mode on the GH2). This is a GOP 3 hack so I believe there are still B and P frames and it is not Intra. However, the resolution is exceptional, motion handling is fantastic, and it's nearly as good as the higher bit rate Intra hacks but with an economical average bit rate of 40 mbps.

You can find the Natural hack or setting here (Natural v2.11):

http://www.personal-...ic-series-5/p13

With this hack you have a versatile m43 camera that can shoot stills, macros, and well-stabilized video. The kit lens (14 to 42 or 28 to 84 in 35 mm equivalent focal lengths) is quite good for video and has good OIS. I have the fisheye and the 45 macro from Panasonic, and have been shooting topside telephoto with Canon L lenses and a cheap adaptor. It's an incredible piece of kit for the price. One downside is that you may find some blue banding because the codec is still only 8 bit 4:2:0. I have been told that you can get good corner to corner sharpness with the Nauticam ports (domes and semi domes) if you stop down to F11 to F13. I frequently shoot landscapes stopped down to F18 with great detail and resolution in video mode. Looking forward to getting mine soon. If you are going to use a hack, read up on the threads from the link above (there a number of quirks, one of which is that you always have to move from the next highest ISO to the one you want to use to avoid the ISO bug that causes noise, e.g., when you turn on the camera, set ISO to 200 then move it to 160 - you always have to do this for the cleanest image.)

Here's some telephoto clips I shot in January with an outdated hack that had some issues. Cadence problems you may notice are from using high shutter speeds and problems with the earlier settings. With the GH2 extended teleconversion mode you actually get full 1920 1080 video with a focal length multiplier of 5. Using a 300 lens and 1.4 converter gives you an effective focal length of 2100 mm:

[vimeohd]36640984[/vimeohd]


Cheers,

Pat

Edited by scaper, 15 April 2012 - 10:59 AM.


#11 scaper

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Posted 15 April 2012 - 09:13 AM

Some advantages of the hacked GH2:

lighter, smaller camera and housings than 5dII
AF is available in video mode but is slower than with a camcorder
pixel binning instead of line skipping leads to far less moire than with 5DII


HDV Diver, are you using autofocus? If so, how well is it working for you underwater?

Here are 2 more sample vids of a snapping turtle underwater and an Amazon fish shot through aquarium glass with AF on and kit lens with an outdated hack and ISO of 1200 to 1600 as I recall. The latest hacks have better detail, motion, and less macro-blocking in shadows:

[vimeohd]40401724[/vimeohd]

[vimeohd]40405537[/vimeohd]

It's only a coincidence that I used the Aquarius hack in an aquarium :P
Aquarius is a high bit rate Intra codec, but is inferior to the latest hack offerings.

One more shot with kit lens shot into an aquarium. The GH2 doesn't have the dynamic range of its more expensive brethren, but apparently the latest hacks improve this as well. Everything I have shown here was shot in 24P. The kit lens in autofocus mode seems to latch on to backgrounds.

[vimeohd]40408202[/vimeohd]

Pat

Edited by scaper, 15 April 2012 - 10:53 AM.


#12 scaper

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Posted 15 April 2012 - 11:04 AM

Can the hacked GH2 deliver 1080 60p?


It cannot. It will do 720 60p. Most of the hacks have focused more on 24p and 30p quality improvements. The latest 720 60p settings are getting much better, but these are the ones most likely to lock up your camera, create on-camera playback issues, or fail to span (make files longer than around 4 gigs) depending on the max bit rate of the SDHC cards you use.. 1080 60i is fairly lousy in all the hacks I have tried - lots of artifacts.

Pat

#13 scaper

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Posted 15 April 2012 - 11:07 AM

Mostly using an old converted Subal F4. Recently bought a Nauticam...very well made housing, just a pity the dome ports are plastic. I'll probably use it more when I get around to making an adapter for my Subal ports.


Kevster:

I'll try to get some videos up on Vimeo asap, but in the meanwhile here are some random frame grabs:



I would love to see some of your clips. I know it's time consuming to get them loaded - no hurry.

Pat

#14 HDVdiver

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Posted 15 April 2012 - 04:33 PM

HDV Diver, are you using autofocus? If so, how well is it working for you underwater?



It generally works very well with the 7-14mm that I normally use for wide/medium scenes. AF speed and accuracy noticeably improves when the ambient light is good or when the video lights provide a good fill. As with any AF system mid-water work with sharks, etc can be a challenge so I tend to use MF under these circumstances. Importantly, the actual AF area/location can be user altered according to need...which often improves accuracy under difficult lighting conditions.

Some Lumix lenses AF more accurately/faster than others; the 7-14mm is a remarkable lens in every sense...the Olympus 12mm f2 is also very good.

For macro I always use two LED lights so the AF (14-45mm+Diopter; 45mm Lumix/Leica macro) works very well.

The other big advantage of the GH2 is that it allows the use of many older type lenses via an adapter. For specific projects/requirements I use some lovely old glass (e.g. Minolta 8mm; Nikkor; Zeiss Contax various mm) in fully manual mode.

Also, should mention that the GH2 has some very useful user settings in the menu setup which have a meaningful influence on how the image (color/sharpness/contrast/noise/WB/etc) looks straight out of the camera. Further color grading/WB/gamma/whatever can be done with a decent NLE (Edius 6 on a Sandy-bridge i7 easily handles 220mbps mts)...but generally what comes out of the camera requires little or no tweaking during editing if the camera is correctly set up.

#15 scaper

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Posted 15 April 2012 - 05:25 PM

HDV Diver, thanks for the feedback on autofocus. It's good to know that it works in many situations.

Pat

Edited by scaper, 15 April 2012 - 05:28 PM.


#16 Davide DB

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Posted 16 April 2012 - 02:41 AM

Currently I'm using Driftwood SEDNA A INTRA in HBR mode 30P. I get about 75Mb/s.
At the beginning I was working at F3.5 which is inusable (I'm a noob). Now, with my Lumix 8mm I stay F8 going hyperfocal. If I need, I just rise the ISO.
It's incredible how the shoots keeps well in post. I use Edius which loads and works AVCHD like a breeze!
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https://vimeo.com/bocio/

#17 cbells

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Posted 16 April 2012 - 03:31 AM

HDV Diver, what diopter are you using with the 14-45mm? Is it a wet or dry diopter? I am trying to find a good macro lens setup to use with a 10Bar housing.

Chris

#18 HDVdiver

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Posted 18 April 2012 - 12:30 AM

HDV Diver, what diopter are you using with the 14-45mm? Is it a wet or dry diopter? I am trying to find a good macro lens setup to use with a 10Bar housing.

Chris



Diopter is on the lens inside the port. I prefer the two element apo type (e.g. Marumi) but even a decent (Nikon, Hoya, etc.) single element optic will do a good job.

#19 DrMark

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Posted 23 April 2012 - 08:38 AM

Hi HDV Diver,

I have been considering going with a hacked GH2 for a while. It is fantastic to get some feedback from someone with real experience with underwater video. Can you say a little more about the white-balance (limitations or abilities)? Also, for macro work, do you think the 45mm macro is any better than the 14-45 with a diopter?

BTW, I also dove with those whale sharks in April 2011 from the Damai. It was a fantastic experience (and the Damai had 24 hour power 8-).

--Mark.

#20 kun1

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Posted 23 April 2012 - 09:02 AM

Any chance of some footage from your time in indonesia? Would really like to see it :)