LXD-75 w/ Stellarvue 102ED Hardin 10" Newt Antares 8" Newt Celestron 102mm refractor Canon 300D, Meade DSI guiding Canon T2i
Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics Engineering = Taking what you have and making what you need.
"A telescope is either good or cheap, not both" - but sometimes you get lucky!
Quote:Ed Jones makes a 4 inch 80 footer most used for solar observing
-DannyMy warehouseMy Channel
"Many a night I saw the Pleiads, rising thro' the mellow shade, Glitter like a swarm of fire-flies tangled in a silver braid." Tennyson: Locksley Hall
Quote:Dave, your red focuses roughly double the airy disc, and the blue, maybe 5x.***** From Tavi's comment, I've often wondered exactly -WHEN- these plots could be correlated with what could be construed as "objectionable" or "noticeable". (where's the threshold?) In other words, the design is no problem, but knowing what's good enough..... My achro could likely be used at a much looser (shorter) design but....Mark