patrick023 wrote in post #15692520
The viewfinder has a transmissive LCD, so it needs power otherwise it appears dark. As far as the battery drain issues goes, it could be a bad battery or if you're using a grip, try it without the grip.
This is correct. It's the transmissive LCD. The viewfinder will dim down when the battery is removed or completely dead. When a charged battery is reinstalled, even with the camera turned off, as soon as you close the battery door the viewfinder will brighten about a stop (Note: There's a microswitch on the battery door, there's also one on the memory card door, but opening it doesn't turn off the LCD. Only the switch in the battery door turns off the LCD). The indications on the focus screen LCD (i.e., the grid, if using it, and the AF point boxes) are only active when the camera is on and awake.
Yes, there's always a small amount of drain on the batteries, keeping the LCD on. It's not much drain, though. I've had a 7D sit unused for over a month and only then did the two Canon LP-E6s need to be charged (camera is gripped and there are two batteries, so if not using a grip it might need a charge sooner). There was still enough power remaining to take some shots. I wouldn't call it fast, by any means.
I also agree. It has nothing to do with the lens. It's not stopping down. The same thing will occur whether a lens is on the camera or not.
If your batteries are draining rapidly, either they are getting old and need replacement, or your charger isn't up to snuff for some reason, or the camera itself is using more power than usual while in sleep mode for some reason. I only use Canon OEM grips and batteries, don't know about third party batteries and grips. There may be some issues with some of them, too. I know some 3rd party LP-E6 clones don't report/register correctly to the camera. I'd be concerned about those. They mustn't have the circuitry of the OEM or maybe are programmed incorrectly.
I also can't say what the lifespan of a 3rd party battery might be. I've been using a dozen LP-E6s in my two 7Ds and 5DII for over three years, some close to four years, and have taken approx. 200,000 shots with them, between the three cameras. The batteries still charge just fine and I get upwards of 1200 shots per battery per charge (in the 7Ds). I'm also using OEM Canon chargers.
It doesn't really matter if you turn the camera off at the switch, so long as the camera is set to go into sleep mode fairly quickly. I very rarely remember to turn my 7Ds off. Sometimes I do specifically to run the cleaning cycle. But more often than not I put them away with the switch on, since it doesn't seem to matter... sleep mode conserves battery charge just as effectively.
Since 7Ds wake up almost instantly at the touch of any of the buttons, I have mine set to sleep in the shortest possible time (2 minutes?).
It is amazing how much you learn about the 7D by reading the manual, even after you had one for a long period of time and thought you knew all there was to the camera. 
