Particularly handy and easily transportable, binoculars are the ornithologist's basic equipment for observing birds within a hundred meters radius (330 ft). Unlike the spotting scope, they give the ornithologist an adequate width of field that allows him to easily and instantly find and frame his target, even in movement. Used outdoors in contrasting climatic conditions and diverse and often humid environments, binoculars must - beyond their optical magnification, brightness, and minimum focus performances - present robustness, waterproofness, and lightness qualities.