If you want software control. The current CHDK version of USB remote operation introduced a modular concept for the selection of what device is connected to the. Tacho pro mileage correction tool.
Andrew Reid in his review 'Why you’re better shooting video in stills mode on the Sony A7S' on describes a very interesting method and points out one of the many weird deficiencies/annoyings of A7S. Some of these issues are deal breaker for many. Still, despite these problems the majority (Andrew Reid included) who owns the camera uses it and tries to find workarounds or adapt his/her shooting practices to the camera, since the camera provides a number of unprecedented brilliant and unique features that the competitors cannot even come close to.
Since Sony is far the most innovative photo-videography gear maker, just like most of their cameras the A7S is simply a Proof-of-Concepts device, too. Because of the fierce competition and speedy technology innovations Sony does not have time to make a completed product, Sony does not release firmware updates to make existing customers happy and loyal. I guess many A7, RX1, A7R, VG900, VG30, A6000 owners would be terribly satisfied, if Sony had released a firmware update with XAVC-S video. At the end of his review a number of positives and at least as many hitches of the A7S have been listed.
Many brilliant photo-videographers on this forum, highly recommends the A7S, since today it is far the best general purpose small form factor FF camera both for photography and videography/cinematography. Still, I don't feel comfortable with buying a $2500 gear, which later will be abandoned by Sony, which happened with nearly all of their high end cameras: VG900, VG30, FS100, no firmware updates to make happy customers; zero after-sales support from Sony. I had a look and tried gear from other makers, but the grass is not greener there either, no way: Fuji/Olympus - pathetic, Panasonic tries to compete with Sony but no APS-C, no FF, a dead-end; Canon/Nikon simply cannot get rid of their stone-age bulky gear with terribly/artificially limited functionality.
After reading the 'Shooting with a 4K pocket camera – the exceptional Panasonic LX100' on I had exactly the same feeling as with A7S: LX100 is purely an expensive Proof-of-Concepts consumer device, either. When these and many other cameras are released they are so incomplete that the majority of the enthusiast community immediately start waiting for an updated version, but in 99% this will never happen. I think I picked a wrong recreational activity: photography and videography are all about expensive consumer gear. Miki PS: The reason I write this here is that, I use DPReview as my journal of progress, thoughts, questions about photography/videography. Facebook is completely unusable, just lik EOSHD and other forums.
Miki Nemeth wrote: Since Sony is far the most innovative photo-videography gear maker, just like most of their cameras the A7S is simply a Proof-of-Concepts device, too. The biggest single issue with the A7S is, IMHO, the lack of built-in 4K recording capability. It's only because of this that I'd consider it a 'proof of concept' device. Panasonic tries to compete with Sony but no APS-C, no FF Sony doesn't make any medium format cameras, does this mean its products are all inadequate? M43 is more than sufficient for many people. If you're not among them, that's fine - but it doesn't mean the camera is lacking - it simply means it's aimed at a different target audience.