https://www.ebay.com/itm/3D-Rig-Stereoscopic-support-with-mirror-stereo-camera/323878737054?hash=item4b68ad549e:g:nFUAAOSwHzNdSu0Q

The Pocket is only $500 USD / £390 UKP this summer (very limited availability, buy now!) .

Frame Sync is the big problem:

Syncing two cams for 3D cannot be done in post - they need to be synced at the pixel level, ie. each camera should begin each frame at exactly the same time. In other words, this is a fractional-frame problem; but you can only correct whole frames in post (not counting pixel interpolators like Twixtor which can cause unacceptable artifacts in 3D).

Pro cameras are synced with 'Genlock' - basically a connection between the two cameras that tightly synchronises frame capture. Without this, the cameras have a random gap between frame starts, anywhere up to 1/2 frame. So if you shoot 24p, the cameras will be randomly out up to 1/48th of a second, and you have no way to predict what that error will be at any given time. In 3D this is catastrophic, at least if there is any significant motion in the frame. The delay pushes moving objects forwards or backwards in 3D, and can also cause a weird shimmering effect. And forget high motion which looks awful.

Solutions:

1) hardware mod: do true genlocking by linking the cameras' capture timers or master clocks somehow at the circuit board level). This is perfect, but tricky/risky and requires skill and experience.

2) Simul-power workaround (this is what we use on the Panny GHs, and works on many others): you power-up both cameras at exactly the same time (usually with external power and a dual-switch or a custom circuit). Many cameras synchronize their frame capture from a global running clock, which is initialised at boot and never changes. So it doesn't actually matter when you trigger record - the first frame capture is always locked to that clock (ie. it waits for the next frame 'slot' before starting recording). By simul-powering the bodies, those clocks start in sync on both bodies and frames are synced.

we don't know if this works on the Pocket yet.

Downside: as no two digital clocks run at exactly the same speed, the bodies slowly drift out of sync. How fast depends on how closely matched the bodies are - people usually try to get consecutive serial nos., hoping that the eletronics components are likely from the same batch and so a close match. My badly matched (2 month apart) GH2's are good for about 4-5 mins before the drift becomes bad. Apparently some drift far less. So you have to keep power-cycling.

Problem: The Pocket only powers up when a button is pressed ('soft' power). It needs to power instantly as soon as external juice is on (one idea, permanently tape the power button down - does it work?).

3) LANC. The Pocket apparently responds to the LANC 'record' command (but not power cmds). If we're really lucky and this resets the frame capture timers (unlikely), it might be enough.

4) Firmware:

If the capture timers are NOT reset by capture start, BMD could add this to a firmware update. Then LANC-initiated record would always start in sync (subject to gradual drift) - much nicer than having to power-cycle all the time. This might be super-easy for BMD to do.

Of course some kind of true hardware sync option (maybe via the USB or LANC ports) would be best! BMD could probably do it if they wanted to - contact them if you want this: http://www.blackmagicdesign.com/uk/support (without demand it's unlikely to happen):

Exposure / Zoom sync:

Frame sync is the most important, but it would also be much nicer if exposure (iris, ISO, shutter-speed), focus etc settings could also be synchronised, ideally in real-time (one body acts as master, one as slave). Firmware or LANC command additions could do this.

With the pocket's small size, ultra-light and compact SBS (side-by-side) 3D rigs are possible. With 'body stacking', you can even get the lenses as close as around 70mm! With Speedboosters and fast lenses you can do lowlight and shoot wide (my target), and you have 10bit ProRes and 12bit RAW. Let's make it happen!