Hello! I'm looking for a copystand with what I can only describe as "geared height adjustment". What I want to do is set my macro lens to a certain magnification, then focus by moving the entire camera up or down. Obviously, this is only practical if I can smoothly make micro-adjustments to height via some sort of geared mechanism. On B&H, the Beseler CS Digital/Photo-Video Copy Stand description says "A rack and pinion elevation system positions your still, digital or video camera where it can be easily locked into position". I think this is what I'm looking for, however...it costs $800. Is there an affordable copy stand with this feature? Is there a way to DIY something like this?