Re: the Orion the Orion Ultrascan 80, see prior page (and one day I might take the time to figure out how the MultiQuote function on CN works )
So it says. I’m surprised because the one I looked through certainly wasn’t. My Vixen ED102SS is an F6.5 and performs every bit like a very good apo. The 80mm Orion I remember wasn’t as good as my TV Pronto as far as color control. Anyway, it was no where near apochromatic. Good ED glass is like FPL-53 and approaches fluorite in optical performance. I think back in 1990, ED was just a buzzword that didn’t mean much in real life. I remember having some Orion ED eyepieces from the late 90s that were nothing extra. Then again, Orion has always ‘laid it on pretty thick’ in their advertising copy.
It's possible that specs, and by that I mean the stuff written on paper (or with pixels these days) that tells how to make something predicted an APO telescope. But not everything as-built performs according the the Platonic Ideal in the specs.
It true of cars, electronics, fast food, some recent movies...
Edited by Littlegreenman, 14 October 2021 - 06:35 PM.