TIL Tele Vue founder Al Nagler designed optics for visual simulators used to train astronauts in piloting the Gemini spacecraft and the Apollo Lunar Module. It allowed training astronauts in the simulator to ‘fly over’ the images of the Moon as though those images were at infinity
https://astronomynow.com/2022/03/08/reviewed-tele-vue-apollo-11mm-commemorative-eyepiece/