There seems to be a strong "pro GH4" culture in this forum. Personally I feel that the A7S has more to offer me, I have one on preorder.
With our studios it's not a gh4 bias, but I have produced really interesting work with the gh3.
As I mentioned I have four 43 bodies and about every m43 lens so it makes sense to go with the gh4 but I held back.
I want to test the A7s, even though it will double my costs to switch out systems.
The upside of the gh4 is
1. the auto and touch screen focus that covers the full frame.
2. The range of decent glass, though the 2.8 zooms are slow for this format. For a cinema look you really need to be at 1.2 to 1.4 primes on most of the normal range lenses.
3. most peripherals carry over from the gh3.
4. 4k internal recording for a small form factor.
5. Very well thought out ergonomics on the camera
The downside of the gh4.
1. ISO, for heavy grading 800 is probably the high end, 1000 is stretching it for video with heavy noise reduction.
2. the crop factor. 2x is difficult, 2.3 x on the gh4 is brutal. As you mentioned a 9mm is 23 in ff terms and has huge glass for this camera. Also longer than 200mm equivalent is the top semi fast lens that will autofocus. Pulling this type of selective focus is not the easiest thing for a gh4 sized crop. The top is a fF 35mm camera, the bottom a red one with a 35mm at F2.
3. Only two versions of 4k compression.. Uncompressed to a external device, or highly compressed in camera. Both offer their own challenges.
You have to work an uncompressed project to really understand the size.
4. I looks like a little 5d3. Not that that is the most important, but it's not a looker.
5. to get xlr sound in, on two channels even in scratch form requires the yagh device that's the cost of the camera, or a third party convertor.
6. Once again 2.3x is a heavy crop and I'd be very surprised if Panasonic doesn't offer some kind of bridge camera between the gh4 and the $60,000 varicam with a super 35mm or aps C format.
7. if you pull back to allow for edl stabilization your crop is even more severe.
The A7s
1. It's not out so who knows.
2. Lenses are roughly 1.5 to twice the price of the gh4 and zooms will be front heavy for devices like hand held stabilizers and drones.
3. No touch screen focus., which until you've tried it, you won't know what your missing.
4. It seems a little rushed to market and accessories from Sony are to come, always to come.
5. The $2,000 Shogun to get to 420 4k is going to put the price double the gh4. Actually across the board fully kitted out your double the gh4 in price.
6. Higher iso is great for certain situations. Makes night shooting with small leds a breeze.
7. I think this is also a bridge camera.
For some reason, even at much higher costs, I didn't lose any sleep over buying our REDs. I knew they were professional and would last a long time, even with the X sensor because really who is going to beat my door down for 6k footage?
Buying these small electronic cameras just sends me crazy because something is always held back, waiting for the next 18 month change.
I feel like I'm sort of being played and if I learn one more menu system of a camera I'm going to have to build a flip chart.
I personally feel apsc or super 35mm (whatever that is) is probably the perfect motion format, but given that, we're still kind of working off old film format thought.
The gh4 could be thought of as a digital super 16 but the file doesn't look like super 16 film. The A7s is probably too large but motion picture film cameras were most constructed due to costs of film. If film was never an issue I really wonder if 35mm film cameras would not have run a horizintal ff still 35mm size, verses running the film vertical.
Everybody talks about 24 fps like it's a holy grail, but I've shot and edited 24 and 30 fps and it doesn't seem to be much difference, other than smoothness of titles and horizontal scrolling.
What gives a cinema look is quality of production, lenses, format and grading, much more than fps.
IMO
BC
P.S. If you have a good story, and good production values and are shooting for yourself in a closed loop and/or you are your own client, then you can use almost any camera.
lately or at least for the last two years, I've heard time and again for large projects, blowback if you say your shooting with a dslr, regardless of the dslr.
It's not that they're bad, that covers a lot of territory, but well paying client's expect professional production, including cameras. They might or might not know the difference between a REd or Alexa, or an F55 but they assume professional cameras bring with it professional results and in some way they are right.
The things is we shoot so different today and it's not unusual for us to use the gh3's, two to three REDs, even a go pro from time to time and though I own, renting or owning makes not difference to a client, as long as they feel they get the level of production they desire.
Actually the rule is to offer more than they anticipate.
But at the end of the day, it's all about the final story and how it's presented.