I just received the new Atomos Shogun 4K Recorder / Monitor and obviously I plan to pair it up with the Sony A7s to utilize it's 4K Video feature (via HDMI only), and also test out 10Bit 4K via the GH4.
For something this heavy, it's probably not a great idea to mount it directly to the Hot Shoe of the camera, so you'll need to look into using some type of accessory mount or Camera Cage. Here's a look at two Varavon Armor Pro Cages designed for the Sony A7s and Panasonic GH4.
Instead of a fairly large generic shell, each Armor Cage is custom designed only to fit a specific camera. This allows the cage to be remain very slim and allowing full access to the camera's dials, inputs, and doors. Each Varavon Armor Cage comes with a leather Hand Strap, while some packages offer a Top Handle and optional rotating ENG Hand Grip.
To maximize the run time on these cameras (I really need one for the Sony A7s), Varavon also offers external battery power solutions for many types of cameras.

Varavon Sony A7s and GH4 External Battery Package
For more information about these cages and optional accessories, check out the Varavon website (here).


Varavon Armor Cages for Sony A7s Pro and GH4 Pro

Emm
Post author@Jim - Not sure what videos you've seen but that handle is solid.
jim
How durable is that top handle, it looks flimsy in some of the videos I've seen on it. I plan on using it for skating as a follow cam.
Emm
Post author@Jason H - Top handle 1 screw. ENG grip is two screws but need to get the camera out to get to it.
Jason H
Hey Emm,
I really like that ENG grip, makes A7s much easier handheld. I'm thinking of buying this cage, one question though, how easy is it to mount the cage body onto a gimbal like Came 7800?
I'd assume you have to take off the ENG grip and top handle, but it looks like it's quite easy to do that with 1 screw?
Emm
Post author@BlackBeltJohns - I don't think the QV-1 will fit back onto the camera once it's in a cage.
BlackBeltJohns
Thanks for the review. I use the Kamerar QV-1 M on my A7s. Do you know if this will still fit around the cage, as it attaches to the bottom of the camera?
Ty
One thing I always forget - and that most people are unaware of before buying the Metabones adapters/speed boosters - is that the threaded mount on the bottom of the adapter is removable. So if that block of metal is in the way for certain setups, it's nice to know that it can be removed.
Sven
Have you tried the Varavon battery?
Somebody at the BMCuser forum posted a review of it a while ago. Saying the build quality was really bad. But I see now it has a new mount.
Emm
Post author@T22 - There is only so much you can actually 'mount' to a cage regardless of how many threaded holes are available. With the equipment I use, I don't ever feel i'm lacking any mouning options.
As far as the other cages go, they are certainly more expensive than the Varavon, and the Armor Cages come with a lot more parts Top Handle, ENG Grip, Hand Strap, HDMI pinch, Audio Pinch, etc. I see on the Viewfactor review there was a problem accessing the audio port on the GH4 as well. With the slimmer form factor of the Armor Cages it's also easier to fit in my LowePro FastPack 100 (mini backpack) without taking anything apart.
T22
Emm,
It looks like the Varavon Armor cages are working out pretty well for you. Are you hampered any by the lower number of access points on the Varavon cages versus other form-fitting cages like the Contineo GH4 cage https://vimeo.com/103519327 or the Motionnine Cubecage https://vimeo.com/99598743
Thanks