TeleVue founder, Al Nagler, eagerly pushed Ethos designer Paul Dellechiaie to extend the new 3.7mm focal length to reach 110°, the same field size as the LEM Simulator optics Al designed 45-years ago to train NASA astronauts for lunar landings.
The 3.7mm Ethos-SX is designed and crafted to combine its exceedingly wide field of view with all the contrast, color-rendition, distortion correction and center-to-edge sharpness needed to achieve that natural view. 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. The 3.7mm actually has more TFOV than our 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 (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|