This ring system has an inside diameter of about 102 mm. This is the perfect size for holding our 80 - 85 mm guidescopes, finderscopes, or telescopes. It will also hold our former model SV90T telescopes either in aluminum or carbon fiber. It will not hold our new version SVX90T, for this telescope use the R120LV guidescoe rings.
When mounting a guidescope on top of another telescope, it is necessary to use adjustable rings. Adjustable rings allow the finder or guidescope to be moved slightly in relation to the main telescope. This is necessary because if non-adjustable hinged rings are used, the two instruments will never be pointed in precisely the same direction. When using a guidescope as a super finder, adjustable rings will allow the user to make sure each telescope is centered on the same object. When doing astrophotography, adjustable rings will make it possible to point the guidescope at a relatively bright guide star while the main telescope is centered on the object being photographed.
In order to use this system, mount the rings by inserting the rear of the finderscope into them, DO NOT remove the dewshield of a finderscope as the lens will fall out. The straight through finder will slide into the rings. It may be necessary to remove the back of the right angle finderscope so the prism does not get in the way as you insert it into the rings. Then simply slide the ring bases onto the top rail on your telescope. Stellarvue rails are sold separately. Choose a rail that is the proper length and hole spacing to work with the dual rings on your telescope.