This small Barlow is amazing. It is a true Dakin Barlow in a small package, made with a superb lens, manufactured in the USA. The MDB screws onto the nosethread of a binoviewer or the standard thread of non-Vernonscope eyepieces. Owners of Brandon and Questar eyepieces may add the adapter for foreign filters to Brandon eyepieces to use this MDB or buy the version with Brandon threads.
The goal is to improve the usability of all binoviewers and eyepieces in addition to providing magnification. Screwed onto the nosepiece of a binoviewer, it gives a bit more back focus (focuser in-travel). On an eyepiece, it gives a little more eye relief. It also increases the f number of the telescope, making all eyepieces work just a bit better. An f/6 scope with a 1.5x MDB will become an f/9.
Because of its small size, and the way it screws onto the filter thread of the eyeiece, it fits into 1.25" eye tubes and adapters. Even though it is small, do check when using with a diagonal to make sure you have clearance from the bottom of the MDB to the mirror surface.
Available in 1.25x and 1.5x, which are estimates of the magnifications achieved when screwed onto the bottom of eyepieces. When used on binoviewers, the magnification will be higher because of the longer optical path. For the Vernonscope binoviewer, with an optical path of 80mm, the 1.5x MDB will provide approximately 3.4x magnification; the 1.25x MDB gives about 2.9x magnification.
Please put in comment box whether you want the 1.25x or 1.5x MDB. We recommend the higher magnification for binoviewers to get the most extra back focus.