Tele Vue's Ethos series:
The 3.7mm actually has more TFOV than our 8mm Plössl, 6mm Radian, and 5mm Nagler Type-6! With 110°, the Ethos-SX has 21% more AFOV area than the 100° Ethos design. This permits a nice 62% power increase from a 6mm Ethos, while retaining 68% of its TFOV.
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.
| Model # | ETH-03.7 |
| Focal Length (mm) | 3.7 |
| Barrel Size (in.) | 2" & 1¼" |
| Apparent Field of View (deg.) | 110 |
| Eye Relief (mm) | 15 |
| Weight (lb / oz) | 1.10 / 17.6 |
| Field Stop (mm) | 7.04 |