The Lumicon LD1025 2" LumiBrite Dielectric Coated Diagonal reflects 98% of the light from the telescope's primary optics into your eyepiece.  In this way, you'll hardly lose anything from what your telescope sees. It may be used on refractors and upon Schmidt-Cassegrain telescopes equipped with a 2" visual back (one is listed here as an accessory if your catadioptric doesn't have it as standard equipment).

The Dielectric Coating is smoother and even more durable than an enhanced aluminum coating, providing maximum image contrast.

Lumicon collimates each and every LumiBrite Star Diagonal with a double-pass collimator, ensuring that the light reflected from the diagonal is perfectly perpendicular to the telescope's optical axis.