Panasonic really listen to film deepees on this camera, from the high end of the food chain to the small indie guys and got 95% of it dead on right.
Fred put it in better terms than I, but you don't really need follow focus, matte boxes, etc. They don't do anything and just get in the way of a camera with this size.
You could put PL's and matte boxes on it, but you'd just have a heavy camera that didn't shoot any better, because as crazy weird as the two constant zooms are, they don't breath much and are nice and smooth.
An external monitor might help for framing, while you let the on board lcd pull out to the right and allow someone else to touch screen the focus, if movement of subjects is critical.
Since there is no c-log type of look, the blacks tend to crush a little, at least in fcp 7 vs. out of camera in quicktime. That is really a gamma issue rather than the actual file, as anything put into fcp 7 tends to crush most converted files. (There are gamma corrections in fcp7 to correct some of this . . . sometimes), but the shadows open up well with a gamma filter, or using the 3 way color corrector.
If you shoot for clients, the gh3 won't look as impressive as an Epic of scarlet tricked out for use, but that belies the fact that the file is rich and deep and more moveable than most would think.
You have to be careful in opening up the mid tones as it can give a casted look if you start too saturated and a film type of plug in (like apple color, or red giant) with very minimal grain will go a long way to matching the RED footage, though you use a scarlet that is much smoother than my RED 1's. so matching will be easier.
I very, strongly suggest, going with the pana constant zooms, vs. oly primes. The Oly primes are brutal sharp, but too sharp for digital motion, the panas roll off smoother from mid tones to shadows.
The upside to the oly primes is they are fast, from f2. to 1.4 so you get more focus fall off, but as Fred says you'll end up running a silk stocking filter to match.
Where most people have issues with the GH3 is they tend to treat it more like a pick up and shoot camera rather than a real professional cinema camera. If you give it the same care in set up you do your RED's or an Arri or an F35 (I know those cameras are way up the chain) you'll have moments that you wonder how panasonic does it for $1,200.
One other note, for a lot of movement, turn off the lens ois. It will give some crazy looking movement, more like funhouse mirror than actual jello cam.
The other side of the Panas they are very rugged. I treat mine awful, in comparison to the RED's and they never miss a beat.
Wishing for more, (we always wish for more) the only downside to me with all h264 cameras is the workflow. Unlike the Sony's AVCHD the Pana file is robust and the color very nice, but if they'd only shot straight to prorezz and have gamma settings, two channel sound, I'd probably use them for everything.
Still 72mbs is in the professional range.
Now one other thought (and I don't recommend this but do use it) is the OMD 5. The file is 30 fps only and about 28mbs but the camera has amazing in camera 5 axis stabilization. You'd have to jump around like a one legged man to make them jittery, the I.S. is that good. Downside is they don't track focus anywhere near the panasonic.
All of this makes me respect the RED's more and more, but also makes me wonder why Panasonic just doesn't go another 30% and bust down all the preconceived ideas of what a professional camera is.
If they could add a module right where the optional grip is, that had bnc, xlr inputs, real hdmi ports and a little more solid construction, with a snorkel viewfinder, smpte time code, a detachable lcd so a second person could tap screen autofocus (btw the tap screen autofocus is amazing), Panasonic would be the go to camera or better put panasonic could be the go to camera, far eclipsing arri, Canon, RED and Sony.
There is an interesting article in the NY times about the Cohen Bros. They mention digital vs. film and they're right there is no digital look. Not like film had color and black and white.
I'll shoot a RED and think . . . wow looks like film, then shoot a panasonic and think . . . wow looks like film, then the next scene I'll go s__t looks like digital.
Or I'll shoot a REd and think wow it hold like a billion stops, that's amazing, then shoot another scene and it's the opposite, like I forgot to turn on the key light or something.
About 10 days ago I had a shot on the beach of a family goofing around. Shooting fast, quick cuts and one scene is great, but I overexposed it. Don't know why, I checked it, it looked good, but when I got it into the computer it was a stop over. It was from the gh3's. I went s__t ruined it, but put it into fcp7, it darkened up, made a compound clip with a track set on multiply and it was all there, rich and deep.
But next time it would be opposite. I'll be the first to admit, I don't understand digital on the whole. I think it's very subject, light, specific to the point it's like it has it's own mind on what it's going to do.
I can force film to do what I want and hold a continuous look. Digital forces me to do what it wants and I have to find a way to fix it.
My take from this the gh3's are much better than the RED's then much worse, then much better. It's so scene specific.
Sorry to go off topic.