The more features that get packed into each new generation of cameras, the less time batteries seem to last. Things like liveview, gps, WiFi, NFC, VR/IS, and a host of other doohickies just drain them faster than they used to. Even if your camera doesn’t feature superfluous battery draining features, other things can kill them quickly, too. Shooting video or timelapse with long exposures, for example.
The obvious choice is simple. Take a bunch of spare batteries. But what if you want more time without having to worry about interrupting your sequence to swap out a battery? That’s where USB power comes in. This video from David at 30Five Millimeter shows you how you can get USB power with your DSLR or mirrorless camera with just a dummy battery and a $5 cable.