The PENTAX SD 7x42 ED roof-prism binoculars feature large, 42-millimeter diameter objective lenses. They incorporate ED (Extra-low Dispersion) optical elements – a first for the S-series – for effective compensation of chromatic aberration, delivering a sharp, high-contrast, blur-free view rivaling that of higher-end models, even in lowlight conditions. They provide minimal glare and ghosting thanks to the application of a full multi-coating process to all lens surfaces and a special coating designed to optimize light transmittance. They are designed with a dependable, waterproof body for use in almost all weather conditions and feature a large six-millimeter exit pupil, making them ideal for astronomical observation.