12mm 42° This unique measuring and crosshair eyepiece has virtually limitless applications. The reticle features a 360-degree scale for measuring angular positions and distances in double stars, a scale subdivided into tenths of a millimeter for measuring planetary diameters, lunar craters and their shadow lengths, and much more. The fine laser etching of the micrometer scale on the measuring plate allows for line widths of only 15 microns and line spacing of just 50 microns. This enables the use of smaller guide stars and precise alignment between the lines.