Okay, this might be a dumb question, but I'm a noob, so here it goes. When you are out shooting somewhere and you are going to switch between 2 lens frequently, how do you keep them in your camera bag? Obviously with the front lens cap on, but what about the back? I was out the other day switching back and forth between a zoom and macro lens, putting both caps on and being very careful, but after a while, I started just stick the lens back in my front carry bag, with the glass side down w/lens cap, but leaving the back mount exposed. Then I started worrying about dust etc...so I wondered, how do most people do it? Thanks!