I was reading the F100 user manual, and I came across the above adamant statement several times in it. That caught my attention. I'm still new to the F100 with only three rolls through mine, but I'm far from new to SLRs. I admit that I've used a lot more mechanical SLRs where there either is no on-off switch or at best maybe a collar to lock the shutter button. I am careful about turning off "always on" meters like on the Canon F-1 and the F Photomic heads, but that's to save the batteries and not out of any other concern. Even so, I've never paid any mind to whether or not the body was on when changing lenses. That's extended on into DSLRs and other fully electronic cameras. I do turn off DSLRs to save battery power, but I rarely even turn off newer film SLRs unless I know they're going into a bag or other situation where the shutter button might get pressed. So, needless to say this is a warning I haven't heeded, and I think that I'm not the only one who changes without turning off the camera. I know that folks don't necessarily change lenses that often now given the popularity and quality of zooms with both large apertures and long zoom ranges. That's not me, though-I don't have a whole lot of zooms, and still have a preference for primes. I'm the guy who turns up my nose when I see someone like a wedding photographer fumble a lens change because I make it a point to be able to change 35mm lenses with one hand and without looking(and now habitually do the index dance on Nikons and even try to do it on G lenses). So, given that, I guess I don't see myself stopping to turn off the power. Does anyone here actually do that, or am I the one who has it wrong?