Eyepiece Orion Sirius Plossl 7.5mm Orion Telescopes & Binoculars · Sirius Plossl 7.5mm Key specifications Focal length7.5 mm Apparent FOV52 ° Barrel size1.25" All specifications Elements4 About 7.5mm 52-degree Plossl eyepiece; Orion's standard 4-element Plossl line.