Saturday, 9 May 2015

canon - Can removing the lens while pressing the DoF preview button damage the equipment?


I know there's hardly any risk to your equipment when dismounting the lens while the camera is on, but can you damage it if you dismount the lens while the aperture is closed down?


With the Canon EOS system it is possible to remove the lens while pressing the DoF preview button causing the aperture to not retract until mounted again. It is useful when using EF lenses on non EF bodies, but can this method harm the equipment in any way?



Answer



Not unless you drop the lens while removing it because you don't have enough hands to hold everything.


Seriously, no you can't damage a Canon EOS lens using this procedure. Canon EOS lenses are designed in such a way that the diaphragm is moved in both directions by a micro servo attached to the diaphragm assembly. Unlike many lens designs, there are no springs associated with the diaphragm in an EOS lens, and the connection between the lens and camera is electrical only. There are no mechanical linkages (unless you count the contact pins for the electrical connections) other than mount itself that holds the lens on the camera. The electrical contacts between the lens and the camera body are also designed in such a way that the main voltage pin on the camera is disconnected as soon as the lens is turned and can not contact any of the other pins on the lens as the lens is rotated to be removed.


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