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Micro switches on Canon cameras


It looks like that most (if not all) Canon DSLR cameras have micro switches on their battery doors and the SD/CF card doors. Unless the doors are closed fully, the cameras will not operate. There may be other brands that allow the cameras to function without closing the battery doors if I am not wrong.


From time to time, I have heard that such switches will malfunction and cause problem to turn on the power of the camera. Can the switches be overriden or disabled (say to press down/in permamently) to avoid possible problem ? What are the cons to do so.


Lensrental has an article on 5D Mark IV teardown. (not sure about the forum guidelines if I can post the link but the blog topic is easily googled online) The battery-door-closed-sensor (switch) is deep down underneath the PCB and the card reader. A defective switch (may be just a few cents for the cost of the switch itself)  may cost hundreds to repair.


What really is the purpose(s) of such switches ? Just to save some battery energy ? Please enlighten.



I say forget about the switches, and enjoy the camera.  The switches are not an issue, and they are present for good reason.  The switches seem to rarely fail, no matter the model.  The images sensor is more likely to fail than door switch.


Besides, if the battery and memory card doors are not securely closed, then the weather sealing on the camera body would be compromised, which is why they are present!

"The right mouse button is your friend."

I am not worrying about failure of micro switich sensors. I came across some discussions in this related subject and I am curious to find out the rationale behind this tiny design.


Yeah. "Weather sealing" is probably one of the good reasons to have these little sensors there.


There may be other reasons that I can't figure out.


Thanks for your reply.



Canon probably has additional purposes but the battery sensor switch is used to help protect the electronics from the spikes that will occur when a battery isn't fully inserted and making proper contact.  Removing a card in a write cycle will corrupt the card but this power on card removal can also cause damage and the sensor switch is there to let the camera try to immediately go into a safe mode if the door is opened while the camera is doing stuff with the card.


Micro-switches are extremely reliable with typical life cycle rating for even the lowest rated components in the 100,000 plus range with Canon likely using a far better component.  The life would normally exceed the combined life of a case full of replacement shutter assemblies.  You are more likely to run into issues with the rotary encoders or shutter release button than you will a micro switch.


Any part can fail and the micro switches are no exception but there are far more likely failures that will occur and in typical usage the micro switches aren't cycled that often.  Battery life with my 1DX 2 is extremely long and I don't rotate cards very often and use the ethernet port for file transfer.  If you are using CF or Cfast cards the camera connector for those is far less robust than a microswitch.



EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video

I have never had a micro switch fail.  Probably will tomorrow!  Smiley Sad  I have shot 100's of thousands of photos.

I know the Rebels, mine did, sometimes have problems with the one under the flash hot shoe. A tiny drop of WD40 fixes that.

EOS 1DX and 1D Mk IV and less lenses then before!