Lumicon 2" Multiple Filter Selector

The Lumicon 2" Multiple Filter Selector goes in to a 2" focuser or screws on to a catadioptric telescope's 2"-18 female threaded rear cell.  It accepts 2" eyepieces, but also has a built-in sliding tray which gives users quick access to up to four 48mm (2") screw-in filters.  It is very common to leave one of the slots open, so that you can compare the naked view with various filtered views.

As with any filter selector, this device does add length to the optical path-some 2.62" (67mm) in this case.  This isn't a problem with catadioptric scopes, but users of reflectors without 2.62" of in-focus path length upon the focuser will not achieve infinity focus without the use of a barlow lens.  Refractor users cannot use this 2" Multiple Filter Selector.