| These large finderscope/photoguide telescope mounting rings mount a short focal length refractor optical tube or a small catadioptric telescope on an optional Losmandy D-series dovetail plate. They let you use the second scope as a high power/variable power finderscope for your larger telescope; as a photoguide scope for long exposure deep sky photography; and as an astrograph. The rings are sold as a pair only.
They have a nominal 108mm (4.25”) internal diameter and will hold optical tubes with an o. d. of 2.45” to 4”. Optical tubes with the latter tube o.d. are a very tight fit and allow for very little collimation range. A 3.75” o.d. tube would be a more reasonable maximum. 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 1.65 pounds per set. The height from the top of the dovetail plate to the center of the rings is 2.9”. They mount on a Losmandy D-series dovetail plate with no tools required. | 
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