The battery of Canon 60D and Canon 6D is one of the most powerful batteries used in Canon cameras today. It produces around 1000 shots in real word tests and it is officially rated at 1100 shots on Canon 60D and 980 to 1090 on Canon 6D. GPS and Wifi reduce battery life even more, but how much more becomes an issue when the percentage falls way below 40% on a single battery (without a grip, that is). I recently shot a session outdoors, needing more than 3 hours of shooting with GPS on and I was surprised to have my first battery drained to the bone in such a "short" time. Soon enough I discovered that being inside a canyon with no visible sky and surrounded by rocks gave Canon 6D a hard time finding any GPS signal. Constantly searching for signal made the battery drain in almost 2 hours until I finally switched it off to finish the session without any problems.
Next day I made a similar 3 hour shooting and battery was at 50% as I switched the GPS on for the first couple of shots and then turned it off again for the rest of the session. BIG difference, I am not sure if I ever use the GPS feature for more than the first shots anymore. I can always tag the rest of the photos from the same location later by copying the GPS coordinates in Lightroom, so no worries.
But wifi is another story. The feature is somehow worthless when you shoot in a studio in ehm... burst mode and you connect via a poor ADSL router, as the data takes much time to get transferred to the computer. I used my router to connect to the device and I must say I was puzzled on what to do to establish connection on both ends. It took me more than an hour to configure connectivity, but I was more disappointed when I realized that the transfer rate was very poor and I had to wait for the data to finish transferring.
In addition, not many programs support tethered shooting on Canon 6D, but you can trick the process by adding watch folders on some programs such as Lightroom. I only found native support for tethered shooting on Canon's software and CaptureOne Pro until now. I have not connected it to a tablet or to a wireless card on a computer to further check speed and ease of set-up, but I am planning to check it out if I need to have a studio shooting.
Closing, please visit Tragic Lantern forum and give the guys at least a nice word and a "thank you" for their GPS Auto-off feature. If it was not for that awesome piece of software, battery would last for even shorter periods of time because GPS continues to drain battery even when the camera is off.
