Catadioptric spotting scopes

Mirror-lens

— optical systems that combine lenses and curved mirrors. Actually, the main magnification in such devices usually provided by a mirror, and the lenses play an auxiliary and corrective role. The main advantage of such systems over purely lens ones is a sharper and clearer image — and regardless of the degree of magnification, which makes this option more convenient for magnifications of 60x and higher. In addition, other things being equal, the spotting scopes themselves are more compact and lighter. The disadvantages of mirrors are fragility, requiring improved impact protection, and high cost. Because of this, this option is typical mainly for "long-range" premium spotting scopes.