This request isn't too different from what many astrophotographers want to do. They want to do astrophotography out in the field (away from AC power). The "problem" is that to get really good smooth results, you should ideally capture between 4-6 hours of data on just one object. This is with the camera almost continuously capturing data. No battery will last that long.
Canon's 60Da (the "a" is for "astronomy") comes with the Canon AC adapter (a dummy battery is connected to a power brick which transforms 110 or 220 AC power into the 7.5 volt DC power required by the camera) -- but in the field there's no place to get AC power.
One would think Canon would have made a 12v to 7.5v adapter... but they do not (they make a charger that can re-charge the internal battery from a 12v source -- such as a car -- but not something to run the camera continuously from that 12v source.
It turns out there are some DIY folks who have done this themselves.
What you need is the dummy battery from Canon and then a way to power it.
First, here's the link to the dummy battery: http://shop.usa.canon.com/shop/en/catalog/dc-coupler-dr-e6
The next challenge is that would normally be connected to a power brick that transforms the source power to 7.5 volts -- that's what the camera wants.
For example, as an astro-imager, I'd want something that can run on 12v power. So I'd do a search for "buck converter 12v to 7.5v" and my screen would be plastered with products that all do this. But you'll see it's just a tiny module with two wires in (the source power) and two wires out (the camera power). You'd then have to get the appropriate connectors, probably a project-box, etc. But I can easily imagine being able to build something that you wear under your coat to keep the battery warm and just feed the power cord out to the camera.
As another option... if you can find a way to get to 7.5v of battery power then you wouldn't need a buck converter. e.g. 5x 1.5v AA batteries (in a series -- not parallel) would do this. So I noticed that Canon's battery grips which normally hold two of their E6 batteries will hold SIX (not 5) AA batteries. Six batteries is technically 9 volts -- not 7.5 volts. So clearly there's a bit of a window of tolerance on the camera voltage but I don't know what the voltage range is.
So far as I know, nobody makes a product that's already built and ready to go (and if you find one... please let me know.)
Tim Campbell
5D III, 5D IV, 60Da
