Here's one for the numbers and program-runners...I really love my D&G 6" f/15 achro...in all ways...and its permanently set up and all comfy it its own little roll-off house. Now, if I wanted to step up to an 8", and maintain the same level of "color correction" (yes, I follow all the achro/apo stuff)...I guess I should better say "color performance", what would be the equivalent f/ratio...and likely tube length? I've had several chances at 8" f/12, but timing/$$/experience wasn't right, I like the "kinda almost apo" 
performance I get (yea, I know a color bloom is in there), I liked the light quality vs quantity. What would I need to do to have both at an 8" level? :S 
8O
No..there's no way I could ever fabricate a folded refractor.
FWIW I'm a purely old-skool visual observer, have absolutely NO, NEVER any inclination for photography or imaging, love doubles and the like.
Thanks for your calculations
performance I get (yea, I know a color bloom is in there), I liked the light quality vs quantity. What would I need to do to have both at an 8" level? :S 8O No..there's no way I could ever fabricate a folded refractor.
FWIW I'm a purely old-skool visual observer, have absolutely NO, NEVER any inclination for photography or imaging, love doubles and the like.
Thanks for your calculations
Pat Kelly in Centreville (Delmarva), Maryland. Retired but working second career.
Telescope - 8" f/12 classic achromat refractor by D&G Optical; Manheim, Pennsylvania;
Mount - 1200DA metric black classic equatorial mount circa 1992 by Astro-Physics; Machesney Park, IL;
BlueStar Observatory 13 x 13 roll off by Backyard Observatories; Lodi, Ohio;
Previous telescopes A-Z: Astro-Physics to Zeiss...D&G Optical Aficionado; The Classic Refractor - The telescope everyone wants to have used but no one wants to own.
