Does it use both battiers at the same time? Or does the grip use one battery first and when that is done, it starts on the other one?
How do you know when one of the two batteries is low/needs a charge?
Can you use just one battery in the grip?
Thinking of buying one today, mainly for the vertical grip.. i carry two batteries with me everywhere so i don't really need the grip for the extra length in batterylife.
Thanks in advance.

