Howie Glatter Self-Barlow Attachment

The self-Barlow attachment is a disc with a white screen on the front and a small built-in Barlow lens in the center of the disc. It is then screwed into the Howie Glatter laser collimator (sold separately) aperture and provides a highly compact method for Barlow-collimating.

As with regular Barlowed laser collimation, the shadow is projected onto the screen at the front of the disc at the focuser end so adjusting the mirror at the back of the scope can be difficult in some cases, especially with reflectors having a long focal length.