Designates an optical system that uses both reflective and refractive elements. The optical system may involve some telescopes or cameras which make use of refractive type optics (lenses) and reflective optics (mirrors).
Designates an optical system that uses both reflective and refractive elements. The optical system may involve some telescopes or cameras which make use of refractive type optics (lenses) and reflective optics (mirrors).