RGB Metering & Focusing.
but if its leisurely, like take landscapes, i think off will be good.
dun abuse it can liao
turning off to change lens is to reduce chances of dust sticking to the sensor.
guys, i suspect cssupporter is a troll.
just report his posts, let the mods deal with him. in the meantime, just ignore and carry on. there will always be troublemakers around.
Learn from ken watanabe, he doesn't off his camera when changing lens
cssupporter is de-reg is it? hmmm... all posts suddenly gone.
Anyway, if you are still reading this here are the dusts in your pic.