Tele Vue 3.7mm Ethos SX 1.25"/2" Eyepiece

With 110°, the Ethos-SX has 21% more apparent FOV area than the 100° Ethos design. This permits a nice 62% power increase from a 6mm Ethos, while retaining 68% of its true FOV. The 3.7mm actually has more true FOV than the 8mm Plössl, 6mm Radian, and 5mm Nagler Type-6! In 1¼" mode, it is parfocal with the wide range of 1¼" Tele Vue Plössls, Panoptics, Radians, Naglers, Nagler Zooms, and 6mm and 8mm Ethos eyepieces. The screw-on 2" adapter (included) is designed to make it parfocal with 13mm and 10mm Ethos when they are used in their 2" modes. Focal Length: 3.7 mm Barrel Size: 2" & 1¼" Apparent Field of View: 110 deg. Eye Relief: 15 mm Weight: 1.10 lbs. / 17.6 oz. Field Stop: 7.04 mm