Does a battery drain little power while the dslr turned off?

tecboy · Jan 22, 2015

For some reasons that I have nothing to do. I noticed when I took the battery out of my dslr and looking through the viewfinder, the image through the lens got dark. When I put in the battery, the image through the viewfinder looked normal. Any explanation?

beachrat · Jan 22, 2015

"Doc,it hurts when I do this..."

snowbear · Jan 22, 2015

I thought I read that Canon lenses default to smallest aperture while Nikkors default to largest. Maybe powering down is putting the lens in the smallest aperture, therefore it looks darker.

qleak · Jan 22, 2015

My Nikon D7100 does the same.

I believe this has to do with the viewfinder which has some sort of display in it.

Notice how you can move focus points with an electrical directional switch? I can change the viewfinder as well depending on if I want composition marks or not. This indicates there is an electric display inside the viewfinder somewhere, my hypothesis is it's just above the mirror.

It also has an LCD displaying the number of shots etc on top next to the shutter that goes blank at about the same time. I was a little concerned about slow battery drain when I first got my camera but I've gone months between charges and shot 20k shots in the last year.

I think the screens use about the same amount of power as a pocketwatch. A pocket watch will run for years on a 30-50mAh battery. My Nikon EL15 is a 1900 mAh battery, so I'm not that worried about it.

snowbear said:
I thought I read that Canon lenses default to smallest aperture while Nikkors default to largest. Maybe powering down is putting the lens in the smallest aperture, therefore it looks darker.

My 1st thought to, but my camera this happens without a lens.

snowbear · Jan 22, 2015

Hmmm. D40 just stays at max aperture; but then again, I don't have a DOF preview (other than the danger zone method) or the top LCD. The other two bodies are old enough that you use the aperture ring on the lens.

runnah · Jan 22, 2015

Mine doesn't drain enough to be noticible.

TCampbell · Jan 22, 2015

The only thing in the optical viewfinder that would be illuminated would be the focus points and the display along the bottom that provides exposure and metering display. The screen itself isn't lit by anything other than the natural light bouncing off the main reflex mirror.

Batteries will "drain" for a few reasons...

1) There is a "clock" battery inside the camera and some some models this is a dedicated coin battery... on other cameras it's a permanent battery but it draws it's charge from the main battery. When the battery is in the camera, it's charging that "clock" battery. This is a very tiny drain.

2) The camera doesn't technically power "off" when you turn off the power switch. The power switch on a Canon is a soft-switch and it's technically in a kind of extended sleep state. But again... this is a very tiny drain.

3) On the 6D, the GPS can keep running even if the camera is powered off. If you enable the GPS then it stays running at all times, unless you (a) remove the battery or (b) use the menu to switch the GPS off. For this reason, 6D owners should either remember to do one or the other or they'll put their camera away for the night, wake up the next day and discover they have a dead battery. Canon did this deliberately (I question their wisdom) because it can take a GPS a couple of minutes to establish a position fix. Canon was afraid that owners would switch the camera off momentarily (e.g. to change lenses, change memory cards, or just to set the camera down for a minute.) This would clear out the GPS's position and when they flip it back on the camera would have no GPS position and would need another couple of minutes to re-acquire a position fix. SO.... they decided to keep the GPS running EVEN if you power down the camera with the main battery switch. Owners have acknowledged understand the logic of not wanting to wait a couple of minutes just because you powered down long enough to switch lenses or memory cards... but asked Canon to provide a firmware update with a time-out (e.g. if I power up the camera in a minute... I was swapping lenses or memory cards... if I still haven't powered back up after 15 minutes... I've probably put the camera away and they should switch off the GPS.) Unfortunately Canon has come out with no such firmware update.

4) Batteries will (and do) "self discharge". They will do this EVEN if you remove the battery and let it sit on the shelf.

I have a camera body I hardly ever use and after it's been sitting unused for long enough, I can pick it up and notice that the batteries have drained down a tick. I have to wait a few months to notice to notice this, but it will eventually happen if I wait long enough. It's no big deal. I have lots of batteries and I use battery grips on my two 5D bodies so I have a ton of battery power to spare. I have NEVER come even remotely close to running out of battery power even with a full day of heavy shooting. But if that ever did happen and I didn't have a spare to swap in... the battery grip has a "AA" size battery tray that slide in to power the camera while I recharge the other batteries AND I have the AC adapter for when I'm working indoors (the AC adapter is really only used when I'm imaging at the observatory because the really long exposure times will kill a battery much faster than a traditional exposure.)

Overread · Jan 23, 2015

many modern DSLRs do have an overlay in the viewfinder system and if hte camera has no power at all this will mean that the viewfinder appears much darker than normal. It's perfectly normal and is not linked to the lens aperture at all in this case (for record canons default to wide open).

I got the same shock when my 7D came and thought it was broken - you might also see that the darker view is also a little hazy, again this goes away when a battery is inserted with charge.

Note all batteries do drain down over time - how fast depends on the battery and the camera. I think Caon recommends you remove batteries if they are to be left in the camera for more than 6 months (or a few months). In general this drain down on a DSLR won't be noticeable day to day or even week to week.