Losmandy 160mm finder/photoguide ring set for Losmandy and Vixen dovetails

They have a nominal 160mm (6.3") internal diameter and will hold optical tubes with an o. d. of 5" to 6.3". Optical tubes with the latter tube o.d. are a tight fit and allow for very little collimation range. A 5.75" i.d would be a more reasonable maximum size There are three large hand-tighten adjustment screws with non-marring Delrin tips in each ring. These allow you to collimate the refractor with the main scope optics when it is used as a finderscope, or to aim the refractor off-axis to locate an appropriate guide star or photographic target when it is used as a photoguide or astrograph.

The black-anodized rings weigh 3.5 pounds per set. The height from the top of a Losmandy D-series dovetail plate to the center of the rings is 5.1". With a Vixen-style dovetail, the height is 4.8". They mount on each dovetail plate with no tools required.