Concept: You may know there's a long history of naming eyepieces after their designers: Kellner, Erfle and Plossl, to name a few. In the late 70's I designed an eyepiece sufficiently radical that I dared attach my name to it. Even today, I must admit a little discomfort when talking about "Nagler" eyepieces.

With "Naglers", my aim is to approach the wide angle perspective of naked eye vision, while maintaining the highest degree of sharpness, contrast, and viewing comfort. The goal is to allow the telescope to virtually "disappear," leaving the impact of "spacewalk" viewing. — Al Nagler

To achieve various features requires different design tradeoffs and thus the different types of Nagler eyepieces. The largest possible true fields of view for an 82°' apparent field of view in both 2" and 1¼" formats are achieved with the Nagler Type 5 series, with focal lengths of 31 and 16 mm

Compact size in medium to short focal lengths is achieved with the Nagler Type 6, available in focal lengths of 13, 11, 9, 7, 5, and 3.5 mm.

To achieve eyeglass friendly eye relief without excessively large and heavy designs requires the other two Nagler types. The 22mm Type 4 and 19, 14, 9, 5.5 mm Type 7 with their long eye relief feature adjustable height eyeguards and are best for eyeglass wearers or Dioptrx™ users.