Diagonals
60° Everbrite 1¼" Diagonal Birding Review

Tele Vue has introduced a 60° finder [diagonal] for their scopes that maintains optical quality while making the scopes much easier to use (for many people) in the field. The 60° view is quite natural and makes tracking birds much easier. It still maintains all the advantages of an angled view: ease of use in a group, shorter tripod height and a more stable view, and, for many birders, a more comfortable stance behind the scope.

In my opinion the 60° viewer represents a significant upgrade for any Tele Vue owner . . .

— Stephen Ingraham. "Tele Vue Upgrades! The best view just keeps getting better". Better View Desired (betterviewdesired.com) (April 2003).