# Is this normal



## jaomul (Mar 8, 2013)

Hi All.I picked up my 7d earlier and without turning it on looked through a very dark viewfinder. I thought it had a problem,but the battery was dead so I could not turn it on. Fast fwd to charged battery and when I turned it on it was fine. I turned it off again and looked through a very bright viewfinder as normal. Being curious I removed the battery and it went dark again. I had a tamron 17-50 attached. It seems (and I could be way off here) that the lens closes down when no battery is installed. Is this correct. I also noticed the battery often goes dead pretty fast when the camera is off. Could this be linked?? Thanks for any input


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## KmH (Mar 8, 2013)

Canon cameras do not have a lens aperture motor in the camera body. Indeed, since 1987 and the intro of the EOS system, there are no mechanical connections between a Canon camera and a Canon, or made for Canon, lens.

So yes, if there is no power to activate the lens aperture motor in a made for Canon lens the aperture will stay closed, regardless if the lens is on the camera or not.

Nikon cameras close the aperture when a lens is removed form the camera, because the mechanical connection between the camera and lens is disconnected.
All Nikon DSLR's have a lens aperture motor in the camera body.


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## Overread (Mar 8, 2013)

That's sort of trueish.

There is no mechanics, but by default all Canon lenses (and Canon mount lenses) have the aperture blades set to wide open when removed or attached to the camera. The only time the blades shut is when the camera closes the blades to take a photo or when the depth of field preview button is pressed. All other times the blades remain open. 

If power shuts off the blades will snap open again - there is a trick where you can keep the blades open by keeping the power on and removing the lens from the camera (a trick used by macro photographers using extension tubs without contacts or reverse mounting a lens so that they can close the blades whilst the lens has no camera communication).


That said the 7D also has a mirror assembly that requires power to function properly, even just a trickle of power. Thus without the batteries in or with them in a depleted state the viewfinder image will appear very dark and grainy.


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## jaomul (Mar 8, 2013)

Thanks for the information


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## manaheim (Mar 8, 2013)

KmH said:


> Canon cameras do not have a lens aperture motor in the camera body. Indeed, since 1987 and the intro of the EOS system, there are no mechanical connections between a Canon camera and a Canon, or made for Canon, lens.
> 
> So yes, if there is no power to activate the lens aperture motor in a made for Canon lens the aperture will stay closed, regardless if the lens is on the camera or not.
> 
> ...



*Nikons are bettah.*


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## jaomul (Mar 9, 2013)

manaheim said:


> KmH said:
> 
> 
> > Canon cameras do not have a lens aperture motor in the camera body. Indeed, since 1987 and the intro of the EOS system, there are no mechanical connections between a Canon camera and a Canon, or made for Canon, lens.
> ...



I'm glad you finally cleared that up, people are always argueing about it


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## TCampbell (Mar 9, 2013)

manaheim said:


> KmH said:
> 
> 
> > Canon cameras do not have a lens aperture motor in the camera body. Indeed, since 1987 and the intro of the EOS system, there are no mechanical connections between a Canon camera and a Canon, or made for Canon, lens.
> ...



You mean your Nikon lenses don't keep the aperture blades retracted when the lens is removed from the camera or the camera is powered off?  :raisedbrow:

Incidentally, does anybody happen to have recipe for hasenpfeffer?  :razz:


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## manaheim (Mar 9, 2013)

jaomul said:


> manaheim said:
> 
> 
> > KmH said:
> ...





TCampbell said:


> manaheim said:
> 
> 
> > KmH said:
> ...


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## nmoody (Mar 9, 2013)

TCampbell said:


> You mean your Nikon lenses don't keep the aperture blades retracted when the lens is removed from the camera or the camera is powered off?  :raisedbrow:



Looking at my 50mm 1.8G (motor built in lens) The aperture by default is wide open and only changes when the camera is taking a picture and then goes back to wide open again.


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