Can someone please tell me what 'backlash' is? in terms of focus in cameras?

Question

I know its got something to do with repeatable focus, but what?

Answer 1

Backlash is the amount of free movement or play between a s***w and a nut.  The lenses are moved by a s***w thread, so it's the movement of the lens around the focus point - you can't get a sharp focus because the lens doesn't stay in one place.