Named after their Italian designer, porro prism binoculars are characterized by objective lenses more widely spaced than the eyepieces. Compact binoculars often have reverse porro prisms, with eyepieces closer than the objective lenses. Porro prisms generally offer a rich depth of field, wide field of view, and three-dimensional image.
Named for the roof-like appearance of the prisms, roof prism binoculars have the eyepieces and objective lenses positioned in a straight line. Roof prism binoculars are appreciated for their streamlined shape and durability.