Question: camera opens up and closes down aperture automatically during focusing/metering?

It's the first time for me to notice this on my E-M10.

I was trying to get a shot of an object and the room was dark. So, I brought over a table lamp to illuminate the object.

I set my Panasonic 14/2.5 to f10 and tried to take a picture in A mode. When I point the camera to a dark area of the room, it seems that the camera opens the lens up automatically. When I point it back to the object, it closes down the aperture. All of these without me touching any control.

Is this how it is supposed to work?

I observed the same thing with the 45 f1.8.

This only happened when the lens was stopped down to around f10.

Please educate me. Thanks!

I noticed it after the last firmware upgrade.  Was shining a flashlight into the lens (at an offset) to look at the blade pattern.  I think it's the camera trying to protect the sensor from burns.

I set my Panasonic 14/2.5 to f10 and tried to take a picture in A mode. When I point the camera to a dark area of the room, it seems that the camera opens the lens up automatically. When I point it back to the object, it closes down the aperture. All of these without me touching any control.

Is this how it is supposed to work?

Yes. It's meant to keep the viewfinder's brightness more constant. I don't know about the E-M10, but the E-M1 has a setting "Flicker Reduction" (Menu->Gear-D->Flicker Reduction) that can be turned off if the aperture's 'rattlesnaking' (as some have called it) should bother you. Maybe the E-M10 has a similar setting.

I have wondered if this negatively affects the lifespan of the lens shutter.

And how this affects battery life.

Probably nothing to worry about.