Nearly half a century ago, Al Nagler designed the optics for the LEM (Lunar Excursion Module) simulator that was used to train NASA astronauts how to land on the Moon during the Apollo program. From Apollo 11 through Apollo 17, every astronaut pilot who landed on the Moon trained using Al's optics to learn how to do it.
Years after the LEM program ended, the memory of the 110° view of the simulated lunar surface seen through the window of the LEM simulator inspired Al to develop an "Ultra Wide Angle" telescope eyepiece to approach that lunar landing "simulator experience." That eyepiece was the famed 82° field Nagler. When the first Nagler hit the observing fields, it changed forever how amateur astronomers viewed the heavens. An early customer dubbed it a "spacewalk" view.
But the 82° Naglers, and even the recent 100° field Ethos eyepieces, didn't duplicate the original 110° LEM simulator experience Al remembered so fondly. So Al pushed Ethos designer Paul Dellechiaie to extend the field of the Ethos design to reach a full 110°, the same astonishing field as the LEM simulator. The first result was the 3.7mm Ethos-SX (Simulator eXperience) eyepiece - a Sky & Telescope Hot Product for 2011. Now the 110° experience has been extended with a 4.7mm Ethos-SX.
Essentially, "the experience" is about creating an image as natural as one sees with the unaided eye - with no visible field stop to limit the view. With Paul's help, Al's initial dream for amateur astronomers is now fully realized. The 4.7mm 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.
Beyond the desire to simply achieve 110°, the extended field of view gave TeleVue the ability to produce a superb planetary eyepiece with a deep sky true field of view in a focal length that slots nicely between the 110° field 3.7mm Ethos-SX and the 6mm 100° field Ethos.
The 4.7mm is a 1.25" format eyepiece and is parfocal with a wide range of 1.25" TeleVue eyepieces. It can be used with the TeleVue DIOPTRX eyesight astigmatism corrector. The included screw-on 2" adapter lets you use the 4.7mm Ethos-SX in a 2" star diagonal or focuser.
We don't think we can aptly describe Al's original experience of "flying over the moon" in the LEM simulator, but for the first time, YOU can experience what the astronauts saw four decades ago. For example, with a TV-102 refractor (or any similar 880mm focal length scope), the actual field of view is 0.58°, so that the entire full Moon fits into the eyepiece field - but at a magnification of 187x! Talk about getting up close and personal with the lunar surface!
