Is the mounting screw for tripods always directly on the optical axis?

Question

Is the mounting screw on tripods always directly on the optical axis? I have a D5000 here and in this particular case it is. But can I trust that it's always there?

Answer

I'm assuming you mean the tripod mounting screw thread that's on the camera, not on the tripod. The answer that that is no, not always, although in most cases it will be. I've seen cameras (mainly point and shoot devices) that have the tripod mounting screw located off-center and/or away from the center of the lens.

Check more discussion of this question.