I might also want to carry a secondary compact lens and a flasher. I'd like to choose the smallest bag that fits my gear, so I am sure I don't need a Lowepro Fastpack 350.
Is Fastpack 200 enough, or do I need a 250?
Added (1). I have already checked Lowepro's bag finder, but it won't let me configure whether I want the lens to be attached on the camera, or just separately stored.
I'd like to have the 18-200mm lens attached to the camera, so that I can just take it out and start shooting pictures right away.
Read more: Which Lowepro Fastpack for Nikon D7000 w/ 18-200mm attached?