In the bottom of my accessories case, I have a rarely used Celestron orthoscopic that I picked up already well used in the early 80's. The black cone top is engraved with "Celestron" and "6mm ortho" and is slightly wider than the tops of the modern UO orthos. The barrel is stamped with a circle M, something I have never seen on any other eyepiece. Most unusual, the AFOV is 50-52 degrees, equal to my plossls.
Has anyone encountered one of these. When are they from and what are they worth? Thanks for any feedback.
Has anyone encountered one of these. When are they from and what are they worth? Thanks for any feedback.
