Specifically designed for 1:1 conjugate ratios, Steinheil triplets are ideal for use in relay systems. Utilizing symmetry to correct for aberrations, Steinheils are made from a low index center element cemented between two identical high index outer elements. In addition, each lens is edged down to f-numbers with reasonable aberration correction at increased fields. Decreased diameters allow lens mounting in a smaller space than traditional Steinheil designs permit. BaSF1; nd = 1.626. AR Coated, ¼ wave MgF2 at 550nm. All dimensions are in mm.