When I used DSLR, I never used lens caps, front or rear. On mirrorless, I use rear lens caps, but not front lens caps. I am more concerned about getting dust getting to the sensor with lens changes on mirrorless than I was with DSLR. Is this a legitimate line of thinking? Or is the risk of dust getting on the sensor the same as it was if a mirror were there? Is the shutter closed on a DSLR when not exposing? I would really like to not use rear lens caps in order to speed up lens changes, but I still worry about it. Anyone out there have any experience or opinions?