The Dall-Kirkham type uses a concave elliptical and a convex spherical mirror.
The Dall-Kirkham type uses a concave elliptical and a convex spherical mirror. The Ritchey-Chrétien (CRAY-tee-en) model uses two hyperbolic mirrors and is free of coma and spherical aberration. Both of these are specialized versions of the Cassegrain type, which involves a primary parabolic and a secondary hyperbolic mirror, which reflects light back through a hole in the primary mirror into the eye of the observer. For ten points, name this type of long-range instrument, whose invention was credited to Isaac Newton.
The Dall-Kirkham type uses a concave elliptical and a convex spherical mirror.
{Reflecting Telescope} (prompt on “telescope” or “optical telescope”)