Planning a GH2 outfit

Phil Rhodes · February 18, 2012

And I promised I'd never do this...

I may have a documentary job coming up which needs to be both HD and cheap, and as far as I'm aware the best current option for cheap HD documentaries is probably a GH2. I lean towards it rather than a Canon as it will probably be easier to get through a QC because of the lower aliasing and higher available bitrates with third-party firmware, and because the smaller sensor will make ENG style focus pulling more practical.

The prospect of doing this is slightly alarming as I'm used to a nice full-size ENG camera with nice ergonomics and all the features you need built in, so I'm trying to plan out ways of doing it so I lose as few of those features as possible. I have not used the GH2 in anger and I would love to hear the opinion of anyone who owns one as to whether my thoughts sound reasonable, or if I've missed anything. Paging Mr. DeCrescenzo?

Here's my thoughts so far:

I have a Tascam DR-100 audio recorder. Because this is documentary and not drama, and because there's a demand for quick edit turnaround, I'm anxious to avoid dual system sound and the work involved in syncing up later. My first thought therefore is to use the DR-100 as a phantom power device and mic amp, then attenuate its line output into the GH2's external microphone input. While I would hesitate to do this for a high end cinematic production, I hope this arrangement will give me reasonable results suitable for this sort of job. It would also give me the DR-100's onboard mics, which are as good as any onboard mic on an ENG camera, for general background audio.

There appears to be no way to add external start to the GH2 (to make a lens-grip record button active), at least without going inside and patching wires across the buttons - which I'm not keen to do on a brand new camera.

I understand there is no composite video output when recording which complicates adding an ENG style viewfinder. I have one spare which I'd love to use, but it seems the only option is to downconvert the HDMI. The HDMI mode seems to change when you start recording which would make this even more problematic; some converters don't like either mode.

The only way of getting DC power into it (at around 9V) is using a dummy battery arrangement which leaves cables protruding from the bottom of the camera; this may complicate mounting.

It would be nice to use my 1/2" broadcast lens. I'm not sure if it would cover the GH2's sensor; it's a 20:1 zoom and therefore I suspect it probably wouldn't, at least at the extremes of aperture and zoom range. Adaptors for this lens to Micro 4/3 are expensive and it is not strictly speaking an HD lens. I'm not sure what it would take to make the power zoom active. The other alternative is some older Pentax stuff which has manual aperture control; I have a long and a short zoom, but they're 1980s vintage and may not have fantastic optical performance, especially on a smaller-than-full-frame sensor. I do have access to Canon EF glass but it suffers the aperture control problem in this scenario, to which the only solution is MTFs Effect controller, which is twice the price of a GH2 and another box and cable to deal with.

Right now I also only have a clip-on mattebox, which won't work with most of the stills lenses I have available as they're all external focus.

I'll clearly need some sort of rod system for it to mount all the hydra of accessories, which at this point would include power conditioning, the mattebox, the camera, the audio recorder, and probably some sort of shoulder pad. I would like the shoulder pad to be compatible with the quick-release tripod plate and my existing broadcast tripod.

Have I thought of everything?

Thanks for any thoughts.

P

Freya Black · February 18, 2012

Do you already own the gh2?

I've still got a beachtek but then you would still need mics, seems like your idea might be more straightforward too.

But how about stuff like an EX1...or an older sony HDV camera connected to a hyperdeck shuttle or atmos or pix220 or something?

Shallow DOF might not be the best thing in a documentary situation either but then I don't think the gh2 is quite as bad as some of the other DSLR's in that respect.

Dunno, is it a straightforward doco or something where anything might happen??!

What flavour of HD are we talking?

You mention getting it through a QC so I assume we are talking broadcast of some kind!?

love

Freya

Phil Rhodes · February 19, 2012

It's almost news, it's event coverage. Corporate, but potentially picky corporate. For fifteen days, if it was a broadcaster, they'd be paying an amount of money that would make it possible to buy a basic broadcast camera, and at least write the job off against the acquistion of equipment.

It's only for this reason that I'm thinking buy rather than rent; this job can easily pay for a GH2 outfit, which is very appropriate to the scale of the work, so both the client and I get a better deal. What I don't want to do is spend £3-4k on a prosumer camera, because that doesn't really make sense for anyone. If it did come to that, I might rent. I especially don't want to end up with something that needs P2 or SxS cards, which are just a preposterously expensive way to buy flash storage.

The downside of course is that the list of things the GH2 would need to be really usable is quite long. It's not really a new problem.

The biggest issues in my head right now are lenses and viewfinding. I own a Fuji S20x6.4 in 1/2" mount, and while there are 2/3" adapters to micro 4/3, there doesn't seem to be one in 1/2". That's assuming the thing would even cover a micro 4/3 sensor, although there's always the windowed-sensor mode. I really need to just offer the lens up to a camera and test this out.

Viewfinding is tricky because I'd slap one of the two standard-def mono CRTs I own on it, but the composite output isn't active when recording (a real facepalm, there). There are ways around this. At least some HDMI to composite converters, available for a few tens of pounds, support the GH2, but I don't know in what modes and frame rates it works and HDMI can be tricky like that.

Potentially, being creative and buying bits and pieces off ebay, a rather good ENG rig can be put together for under £1000, overlooking the lens issue. That number is very hard to beat. It just all becomes a bit of a medusa once you work out what you want it to do!

Edit: Wow, B4 ENG lenses are now really rather affordable, and

You can even flip the extender out and select 2x digital zoom on the camera - which is sort of OK because the sensor has enough excess resolution that it doesn't completely destroy the picture - and thereby achieve variable depth of field. Cool, eh?

P

Peter J DeCrescenzo · February 19, 2012

Hi Phil: Sounds like a fun project.

Your idea of using an external sound recorder is good for all the reasons you mention. Unlike a few other DSLRs (very few), the GH2 doesn't support live audio out while recording, so monitoring sound off the external recorder is the way to go. Once you get your GH2, I'd recommend doing some basic sound tests recording in-camera in addition to the external recorder. Connect an output of the ext. recorder through a -40db or so pad/attenuator and input that into the GH2 (w. the GH2's sound recording level set to it lowest setting). The quality of the sound the GH2 will record can be perfectly acceptable for many situations. Not perfect, but not horrible either. And there's no need to sync it in post. But by also recording everything on an external recorder at the same time you'll always have that as a back-up (in case of inevitable cable/adapter failure) or for use when best-quality sound is required.

The sound in this video is an old Sennheiser 100 series wireless lav mic connected via a -40db pad & recorded by the GH2 itself (there's no audio during the opening logo animation):

http://vimeo.com/34923749

Concerning using an external VF with a GH2: I'm not sure, but are the ENG cam B&W CRT VFs designed for use with composite video probably capable of "only" about 500-700 TV lines resolution, or are they better/worse? How does that compare to the GH2's built-in 1.55 mega-dot color EVF? Is the resolution similar? Of course, the CRT VF has definite advantages: Adjustable peaking, can be calibrated, can be mounted at a convenient position, etc. Note that the GH2's EVF displays a bit of aliasing -- much more than what the GH2 is actually recording -- and the aliasing in the EVF can be helpful when focussing.

As for adapting a ENG-style zoom lens: I seen reports online that a few folks have succeeded adapting 2/3" ENG zooms to the GH2's m43 lens mount, but I don't recall examples of a 1/2" ENG zoom being used. I don't know if it can be done. If the 2/3" ENG lens doesn't have a 2x tele feature, I believe the GH2's "Extra Tele Conversion" mode must be used (center-crop sensor mode). Meaning the lens must be very wide at the wide end to be practical, especially for hand-held (or shoulder-mount) shooting. The video you linked to in your post shows that a 2/3" lens with a 2x tele feature can be a workable solution.

A big advantage of using a ENG lens would be the servo zoom, if you can get that to work power-wise.

If the budget allows, it might make more sense to use a reasonably fast, parfocal zoom DSLR lens designed for m43 mount (if auto features are desired), or one designed for old-style Nikon F, etc. for full-manual operation. But of course, no servo zoom. Sigh.

Is "stealthiness" important for this project? If so, operating a GH2 totally stripped down (the camera, not you!) could be the ultimate in stealth. Of course, deciding which bits to omit from the rig can be tough, since each piece of gear is potentially useful.

Cheers.

Phil Rhodes · February 19, 2012

Thanks for confirming my thinking, it's nice to be sanity-checked on this sort of thing. Now all I need to do is go and win the tendering process for the job!

Your idea of using an external sound recorder is good for all the reasons you mention. Unlike a few other DSLRs (very few), the GH2 doesn't support live audio out while recording, so monitoring sound off the external recorder is the way to go.

One thought did occur: if I end up decoding the HDMI for an analog viewfinder, then I'll also end up decoding the HDMI audio. I'm not sure under what circumstances it's active, though.

Concerning using an external VF with a GH2: I'm not sure, but are the ENG cam B&W CRT VFs designed for use with composite video probably capable of "only" about 500-700 TV lines resolution, or are they better/worse?

It's a standard-def viewfinder, which is of course not ideal. That said I'm mainly interested in it for the ergonomics, immunity to glare, and so on. More than once I've found myself desperately cupping hands around the EVF on a 5D and it is not a circumstance I relish in an ENG style situation.

How does that compare to the GH2's built-in 1.55 mega-dot color EVF? Is the resolution similar?

I'm not sure. If the TFT on the camera is 1.55 megapixels, that's about 35% more than a standard-def image, but I wonder if "mega-dot" means that there's actually 0.5 million RGB triples, multiplied by three, in which case the CRT would potentially be sharper - give or take analog losses. But as I say, my principal concern is positioning, glare and ambient light pollution. Does the TFT go away when HDMI is connected?

The biggest issue with running a CRT viewfinder is of course deriving a composite (preferably mono) video signal. The lack of composite output while recording on the GH2 is a major headbanger (it seems to particularly irritate the model helicopter people). The existence of cheap, simple HDMI to composite devices like this one might solve the problem, although they reportedly suffer from the compatibility problems of many HDMI devices. I'd be interested to know exactly what resolutions and refresh rates are output by a GH2 on HDMI in the 1080 (24, 25, 29.97 i/p) and 720 (50, 60p) modes, so I can investigate further.

As for adapting a ENG-style zoom lens: I seen reports online that a few folks have succeeded adapting 2/3" ENG zooms to the GH2's m43 lens mount, but I don't recall examples of a 1/2" ENG zoom being used.

Yeah, I'm becoming resigned to the need to buy a 2/3" B4 lens. Not that there's anything wrong with that: the variability offered by the combination of extender and clean digital zoom is attractive in itself. No longer do we need to choose between an ENG/documentary outfit and one for drama. Sweet.

A big advantage of using a ENG lens would be the servo zoom, if you can get that to work power-wise.

Doable. It's just a hirose connector with 12V power on the right pins, I believe, although I haven't found what I felt to be a suitably authoritative source on that yet. While one was at it, one might also pick up the "VTR" button pins and wire it up to a remote start for the camera (and perhaps the audio recorder). Perhaps you can confirm this - will a normal shutter release remote start the GH2 video recording? Is it just a closing contact?

I'm not bothered about auto features, really, although a really crafty engineer might pick up the lens comms from the GH2, figure out how the iris commands work, and feed that back to the iris servos in the B4 lens...

...but I digress.

Is "stealthiness" important for this project?

No, but it's a nice option to have.

Thanks for your thoughts.

P

Peter J DeCrescenzo · February 19, 2012

Best of luck on getting the gig & on your camera research.

Repeat after me: "The GH2 does not output live audio when recording." Period. Not out through HDMI, not out through its analog audio connector, nada, nothing.

During playback, audio goes out both connectors, but not when the cam is recording.

If I have time today, I hope to do a little test shooting using Vitaliy's new firmware hack, specifically using 30p at around 50 megabits/sec. and recording audio in-camera from my wireless. Walking & talking. Since I don't have a "steadicam" yet, this will likely result in a shaky mess, but be instructive. :-)

Phil Rhodes · February 20, 2012

Do report your findings.

Repeat after me: "The GH2 does not output live audio when recording." Period. Not out through HDMI, not out through its analog audio connector, nada, nothing.

Unngh. The pain.

I'd be interested to know what the results are like in 25p (If you're running the third party firmware, it should be switchable). I'd especially like to know what sort of modes need to be supported on the HDMI output. Finding a converter that'll handle 24/25/30/50/60 in 720 and 1080, i and p as appropriate may be a bit of a bind.

Did we ever reach a conclusion on remote start? Will a normal shutter release do it?

Thanks,

P

Dal Neitzel · February 20, 2012

On syncing up interview...

I understand you are not headed in this direction...but...Maybe in the future...

I recently shot an interview on a DSLR that required quite a bit of coaching with the subject between actual takes. I was using a wireless lav attached to a Marantz PMD660 for main audio and a Rode mounted on the DSLR for back-up. I started the Marantz at the beginning of actual shooting and did not turn it off until the end of the shoot some 35 minutes later. However I did not let the DSLR run continuously. I started and stopped it as needed to eliminate all the coaching between useable answers during the interview. At the end I had 12 clips on the DSLR that matched up with audio somewhere on the Marantz recording. I then used the auto audio sync feature in Final Cut Pro X to match the various clips with the Marantz recording. It did a perfect syncing job with each clip in just a few seconds. I was surprised and delighted. Syncing clips is not the time consuming demon it once was.

Peter J DeCrescenzo · February 20, 2012

Unfortunately, I haven't had time to do much test shooting using Vitaliy's new hack, but one thing I wanted to try was the new ability to shoot in PAL mode with my "NTSC" (US) market GH2, and at a data-rate higher than Panasonic's latest firmware allows.

Here's a brief little 25p motion test. Download the original AVCHD .MTS file from Vimeo to see the full quality. There's additional info about the clip & camera settings on the Vimeo page.

http://vimeo.com/37129095

As noted on the Vimeo page, "The frame-by-frame motion in the original .MTS clip is perfectly smooth. Playback in your web browser might not be smooth for various reasons (Vimeo doesn't handle .MTS well). To see the clip in its full quality, download the .MTS file and view it in the latest version of VLC or compatible editing software."

My understanding is that the GH2 records progressive 25p PAL video in a 50i clip, which FCP-7 can switch to 25p by your changing the clip's field dominance property to "None". There's no quality loss and no rendering required. I believe other NLEs have a similar feature. Please correct me if I've got this detail wrong.

Important: The purpose of this test was to observe 25p MOTION. Among other things affecting non-motion aspects of this video, please note it was shot though a double-pane glass window! :-)

Cheers.

Phil Rhodes · February 20, 2012

That's interesting, thanks for posting it.

Vimeo uses a flash embed, so they are almost certainly playing h.264 and I'd be surprised if it mattered what the upload format was. They're presumably converting it on their server, almost certainly with something like ffmpeg. I see the discontinity in motion, although I see that quite often. I think it's just an issue of Flash not being the world's most sophisticated piece of software as regards putting HD images on the screen 25 times a second. There may be another issue in that Vimeo may be forcing it rather inelegantly to some other frame rate.

I notice a bit of colour aberration, particularly below the yellow mailbox or the green foliage against the road, but I'm not sure if that's lens, sensor or codec.

There is some aliasing visible in the tree branches, but it doesn't seem to have the objectionable colour artifacts that a Canon might give you in similar circumstances. At least, I assume it's aliasing; it might just be compression. I'd be interested to see a zone plate - which I suspect would not be spectacularly good - from a GH2 in video mode. It might be slightly better in the ETC mode, which is reportedly a 1:1 pixel mapping. I've searched but not found anything online.

My subjective impression is that Panasonic's MPEG-4 codec is considerably better than Canon's. Using levels, I can increase contrast to the point where I can clearly see that this clip uses a 12-frame GOP, but it's pretty decent. I understand there are I-frame-only modes available in the third-party firmware and it'd be interesting to see how they hold up to tricky subjects (graduated skies, chaotic motion, etc). At this point it looks a lot more gradeable.

The bitrate on that clip works out to about 3.7MBps (Just under 30Mbps), but then it's fairly static. It certainly is marked as top-field-first interlaced, and putting it on a 25p timeline in Premiere CS5 does cause Premiere to deinterlace it (badly). Interpreting it to 25p does solve the problem.

I wonder if the camera writes original MTS streams or the M2TS version intended for random access (which are often also named .mts). The random access performance when scrubbing is not particularly good, but that could just be a side-effect of the GOP length as much as the need to hunt for frames. Once playing, performance is fine.

Again, thanks for posting it. I wonder if we can persuade you to point it at a zone plate? The difference between standard and ETC mode might be illuminating.

Yours in pixel peeping,

P

Peter J DeCrescenzo · February 21, 2012

Hi Phil: I don't have a zone plate. Is that something that be usefully downloaded from the web & printed on a laser printer? If you can provide a link & instructions I'd be happy to shoot a test for you.

Phil Rhodes · February 21, 2012

Ooh, that'd be nice.

Sure, I've attached a zone image to this post. It's only 1920x1080, so you can probably just display it on a TFT monitor. Frame up such that the camera can see some of the finer lines, then zoom (or dolly) out slowly, watching what happens. It is, of course, essential that the image is displayed precisely pixel-for-pixel. If you zoom in and out of it in a picture viewing application you will get a very nice preview of what a really bad camera will do to it, for exactly the same reasons. This tends to be the case even if your imaging application uses an extremely sophisticated scaling algorithm.

On any DSLR (and in fact disturbingly many cameras in general), "what happens" will be "nothing nice". As the detail in the chart begins to defeat the frequency response of the sensor, aliasing will appear as other circles where there are none in the image.

If you want to be even more depressed about your camera, fiddle it in photoshop until it's red, green or blue against black. Or red, green or blue against white.

Or, if you want to be a cynic about it, green against red.

Or, to really annoy the Red camera company, blue against red...

P

Zone plate image: http://philrhodes.com/client/zone.tif

Peter J DeCrescenzo · February 21, 2012

OK, here's a 1st attempt. Download the camera-original AVCHD ".MTS" file to see the full quality & watch it on a 1080p monitor.

http://vimeo.com/37189570

Recorded using Panasonic's GH2 v1.1 firmware hacked using PTool v3.64d. For this recording, the only PTool setting I changed was to enable PAL 1080p25 recording. I left the data-rate for the GH2's "HBR" mode at the factory default 24 megabits/sec VBR.

This recording was made with the GH2's "ETC" (sensor crop) mode turned OFF. I'll shoot another test later with ETC turned on.

Sorry for the not-smooth zoom; best I could manage with the kit 14-140mm lens.

P.S.: I have Vimeo's "Display at 1080 resolution" feature turned on, but for some reason it's not working at the moment. Download the camera-original file to see full res. (Watching Vimeo's default scale-to-screen-size display mode is fairly hideous.)

Phil Rhodes · February 21, 2012

Thanks for doing that, it's interesting.

Yes, test suffers terribly from the video being scaled in software.

This presents a dichotomy:

- It's terrible

- It's great.

Getting the terrible out the way: a real high end D-cinema camera will naturally do much better than this, although the F35 famously doesn't do that well in this sort of test, possibly due to the unconventional construction of its sensor. It's about as good at this test as some very cheap consumer handycams. What is visible is the fact that it looks like the thing is being scaled up from a vertically squeezed image, perhaps about 800 pixels high. The scaling isn't great, and that 800-ish-line pick of the sensor presumably has some aliasing built into it already. You can actually see this vertical scaling issue in some of the tree branches on that exterior shot. Vertical and nearly vertical lines are smooth; nearly horizontal lines are slightly stairstepped. The same issue clearly exists in the horizontal axis, which is what's putting the extra circles inbetween the real ones more or less throughout the shot, but it's much more subtle and I didn't notice it on real world material.

On the other hand, it's much, much (much) better than any Canon and actually better than some extremely low-cost handycams I've seen.

What's most interesting about it to me is the way the codec just gives up on trying to encode the sea of HF detail at a fairly well-defined point. It's almost exactly three quarters of the way through the clip, and all the fine stuff just disappears like it's been switched off. Not wrong, just an artifact of the technical approach in use, but it's an interesting effect. There are some other interesting DCT artifacts as well, where the almost-diagonal patches of striations end up looking like a checkerboard of individual pixels.

We must get someone to do this with a 5D. And an AF100. And a C300. And an Alexa.

Yours in ever more obsessive pixel peeping,

P

Peter J DeCrescenzo · February 22, 2012

Here's a 2nd test. This time 1080p24 (24p, not 25p) with the GH2's "Extra Tele Conversion" (ETC) sensor crop mode turned on.

http://vimeo.com/37259789

ETC mode is noisier than normal, non-cropped recording modes. For this test I had the cam's noise reduction turned down to its lowest setting (-2). Increasing the cam's NR to 0 or higher (+1 or +2) slightly reduces the noise at the expense of some detail.

As noted on the Vimeo page:

... zone plate graphic displayed on my MBP 17" laptop screen at 1-to-1 pixel size (1920 x 1080), and recorded with my hacked GH2.

To see this in higher quality, download the less-compressed 10 megabits/sec H.264 Quicktime file and watch it on a 1080p resolution monitor to evaluate it.

Camera was mounted on slider dolly about 7-ft. from the laptop screen. Camera traveled about 12" total, pushing in about 6" & pulling back about 6" from the mid (in-focus) point.

GH2 running Vitaliy Kiselev's PTool v3.64d firmware modification software and Panasonic's GH2 v1.1 firmware, enabling recording at 42 megabits/sec VBR (higher data-rates are possible). For info about Vitaliy's software, refer to his website:

personal-view.com/talks/discussion/2317/ptool-v3.64d-topic

Notes: Lens: Nikon 55mm f1.2 SLR lens @ f11, 1/50th shutter, ISO 320. GH2's "Extra Tele Conversion" (ETC) mode on. Full manual "Creative Movie" mode, "24H", Film Mode: Smooth (all -2), iDynamic & iResolution both off. Audio recorded via cam's built-in stereo mic.

Phil Rhodes · February 22, 2012

Interesting - that actually looks somewhat less good than the full sensor stuff. Thanks for setting it up.

It's surprising really how the Canon stuff looks so comparatively un-objectionable, and this is better than that. I need to rent one of these things and shoot some dynamic range charts.

Edit: Dammit, Mitch got there first:

http://www.youtube.com/watch?v=qVcaO2zYB6g&list=UUr1jF09uL7J_evqa_BgoSiQ&index=56&feature=plcp

I burn. I pine.

More edit: Also: Panasonic viewfinder pinouts are a massive pain in the neck.

P

Phil Rhodes · February 26, 2012

Further to earlier discussion, a quick bit of maths reveals that the display on the back of the GH2, which is quoted in the new manufacturer's fantasy measure of "dots", has a resolution of no more than about 960x540. This would imply it had 514,000 or so RGB triples (or about 750,000 pantile spots, if it was an OLED with shared-component pixels, but it isn't) and thus about 1.5M individual TFT elements. This is entirely in line with things like smartphones, which I suspect are probably the real driving force behind TFT panel development since it's such a huge market. The very best of them are 3-4" diagonally and have a resolution of about 960x540, most of them somewhat less.

This is not significantly in excess of the capabilities of a standard-definition CRT viewfinder on paper, although analog losses probably mean the TFT would be visibly better in use.

This is actually quite an interesting field, since we really don't have the technology to make full HD displays that are very small. Even 4 and 6 inch monitors are rarely more than 800 pixels high. The very smallest full 1920x1080 displays are probably the sort of things used on laptops. I think the people who were eventually bought out by Red made a 1280x720 TFT viewfinder, but it was a mono panel with sequential RGB backlighting and therefore suffered from the colour strobe problems inherent to things like DLPs.

Interestingly, it is certainly possible to make a full-res DLP panel that would fit in a broadcast viewfinder, although you would probably be stuck with sequential RGB. I wonder if anyone's done that.