Steinheil System Loupe
The "Steinheil Type" magnifiers are composed of a biconvex lens with high radii of curvature made from the highest quality crown glass and two negative meniscus lenses of flint glass cemented onto both sides of the central positive component.
The magnifier itself is mounted it on a lightweight barrel with a sliding frame, both made of black plastic, which covers and protects the lens surfaces from dust or damage, to some degree even from dark room chemicals if used in a dark room. When slid into the open position, the cover becomes a convenient handle.This pattern of loupe or magnifier has long been used for the preliminary inspection of microscopic specimens. It has also been used by forensic laboratories and police departments for viewing evidence up close at a crime scene.
The Steinheil magnifiers have been made for long life and durability. The sliding hard plastic case protects the relatively soft "flint" type glass from the kind of scratching and marring that would naturally be expected from every day use and carrying around in a pocket. The lens is cemented into a lightweight barrel of black plastic, and when the lens is slid out of the protective handle, the barrel itself acts as a convenient handle for holding the magnifier.