When using my Sony A1 mirrorless camera, when in a dark studio I must set the Live View Display - Setting Effects to Off in order to have a bright enough EVF to see the model or item being photographed when using something other than a constant light source (i.e. strobe). With Setting Effects ON, I get a black or almost black viewfinder since the room (before the flash goes off) is quite dark. With Setting Effects OFF, I get a bright viewfinder that allows me to properly frame the image.
This works perfectly.
My question is - since the camera doesn't "see" thru the lens into the viewfinder like a DSLR (since there is no mirror), what does the camera do to give me the bright EVF? I know it works perfectly...I'm looking for HOW does it work.