14" Strut; 10"XT; 102ES; 22 in Process; 3.5,5,7,10,14,20mm Pentax XW; 17.3 & 12mm Delos; 27mm Panoptic; 20&24mm ES 68; 24mm ES 82; 30mm ES 82; 6&10mm BCO;
David W. Knisely . . . . . . "If you aren't having fun in this hobby, you aren't doing it right." Hyde Memorial Observatory http://www.hydeobservatory.info Prairie Astronomy Club http://www.prairieastronomyclub.org
Quote: Many a risible Coulter from days of yore can do well enough on the quite dim stuff, if well enough baffled. Even the coatings need not necessarily be better than the good ol' standard aluminum, due to the eye being primarily a contrast detector. But if one wanted to compensate for reduced transmission efficiency, an exit pupil 10-15% larger should get image surface brightness up to that of the modern high-reflectance coatings.
I can already hear howls of protest at my heresy. But such reactions are borne of an incomplete appreciation of just how very *awful* is our resolving power at these low levels of brightness/contrast. Sure, the stars will look less sharp, but the nebulosity will be perceived just well as seen through a same-aperture, equally-baffled top-end scope.
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Quote:That's interesting ! I had one of the first order 17.5" Coulters that I collected in Daytona and brought home to UK. Images were a bit soft and I got it refigured but not much improvement. It proved perhaps too big an aperture for suburbia so I went back to a 12" go to SCT and have stuck with it since to very good effect:-)
My descriptor was likely in line with what many might think nowadays, what with so many 1/4 wave and better dobs on offer. I mean, these days what is one's first reaction when encountering a 3/4 or 1wave P-V error? Most would run screaming into the hills!
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Quote:Quote:That's interesting ! I had one of the first order 17.5" Coulters that I collected in Daytona and brought home to UK. Images were a bit soft and I got it refigured but not much improvement. It proved perhaps too big an aperture for suburbia so I went back to a 12" go to SCT and have stuck with it since to very good effect:-)
Same here, Maurice, though I went one step further and had my Coulter refigured twice.
Still there weren't too many other options in the mid-80's and I ended up observing thousands of faint fuzzies with it!
Visual deep sky 18" f4.3 David Lukehurst dob 8" f/6 Dark Star dob 8x42 binos 100% visual observing...
Quote:Bagged it tonight ...