I’ve seen tube rings on refractors that allow a plate to be mounted running along the tube at, say, the 3 o clock position; the idea being that it gives you more space to mount another scope or kit (other than on top of the scope).
I have a control box that I want to mount on my refractor but I have a guidescope on top and I don’t have room.
Although grandiose, you get the idea from this awesome monstrosity
(I don’t have a set up like this by a million miles)
Edited by SimonIRE, 28 June 2020 - 12:27 PM.