I will be traveling to Italy and was wondering about carrying my equipment around in a backpack. I have been reading that backpacks often must be checked when entering museums, cathedrals and other sites. I would be worried about leaving a backpack with expensive lenses unattended. On the other hand, I wouldn't want to feel that I can't visit these sites either, which is the real purpose of the trip. Does anyone have any experience with this and advice? Thanks!