Say I have 2 objects, A and B. I zoom in as far as I can on A, then turn to look at B which is way over there. I can't get any closer to B because I'm at my zoom limit. What I'm looking for is a way to move the camera forward (not zoom) like I can pan left & right. What I have to do to accomplish this is to turn 90 degrees left or right, then move (shift+right mouse+drag) so the camera is closer to B, then turn to look at it.
What brought this up was when checking a design of an enclosure, top and bottom fit. There are several things inside the top and bottom that have to align with a corresponding part in the other half. I got the camera inside the closed enclosure to have a look around, but navigating was a pain because of what I've described.
So, how does one move the camera forward and backward? (Not the same as zoom.)