David Cotterell Toronto, Ontario "If an observer actually sees an object, there is no point in referring to a formula to find out whether he ought to see it; and if he fails to detect it, no formula will ensure his success." - W.H. Steavenson 8" f/15.5 TEC Maksutov 16" f/5 Teeter/Zambuto Dob 66mm WO SD AT 65EDQ APO Refractor Astro-Physics Mach 1 GTO Mount iOptron ZEQ25 mount Canon 60Da
<2 hour drive to gray/black zone “Contrast is not everything. Outside of aperture, contrast is the only thing” -Carl Zambuto
Quote:And comparing a large Newt to a small APO is comparing apples to oranges.
Quote: Quote:And comparing a large Newt to a small APO is comparing apples to oranges.
Maybe comparing apples to peas?
Quote: Some time soon, I will prove my point, period.
Quote: If in terms of "refractor like" one means tight pin-point stars against black with a high degree of contrast with no scatter or softness...
"I have been paddling in the shallows of a great ocean of knowledge." - Sir Isaac Newton * * 15" F4.55 Starsplitter Dob & a Denk II binoviewer * * http://peaceofsky.wordpress.com/ Pacheco State Park Fremont Peak
Quote: Maybe comparing apples to peas?
Quote: The problem is spherical lens surfaces are not that hard to mass produce. The parabolic surface is Harder to have perfect .
Quote:I disagree with the statement that no Newt can equal an equal aperture APO. But it will take a lot of very creative thinking and some hard work to do the job. Some time soon, I will prove my point, period.And judging from the bashing I got on the Refractor Forum a while back, no APO owner will ever admit it.I do concede that an ordinary Newt, as currently envisioned, cannot equal an equal aperture APO. It just ain't gonna happen! And comparing a large Newt to a small APO is comparing apples to oranges.As usual, I will add no further comments to this thread; I have work to do. Ed
Quote:I think one of the main reasons people think that refractors are a step above newts is that they have better thermal management properties by design. The light path is protected from the observers body heat and the light only goes through the tube once. This in addition to the fact that most refractors are smaller apertures make for more steadily stable images so much more often than in newts.
Jeff Morgan - Wile E. Coyote School of Telescope Making
Celestron C11+EQ6, skywatcher /Zambuto 12"dob,watchhouse tracking platform, 16"/Zambuto lightbridge , Ethos's 6,8,10,13,17,21. Naglers 31,26. Lieca ash zoom, televue 2.5 powermate,2"2x powermate .Paracorr type2. Howie glatter 2" laser & Tublug. Lumicon 2" UHC, 03, H-Beta,Televue smoothies ( all of em) , Meade 4000 smoothies ( all of em). That'll do for now.
Quote:I am curious on this topic as I sometimes see that claim by scope makers. I am especially curious as to honest opinions regarding the <f/4 large dobs. We all know you get a brighter image and can see more, but does anyone feel that you get as crisp an image as an APO?
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
Meade 16" f/4.5 Lightbridge M42 w/Paracorr & "Crossbow" EQT-200 Equatorial Platform
Meade AR-6 w/10:1 Dual Speed Crayford Focuser
Meade ETX-125 Terabeam/Wegat
Orion ST80 w/single speed Crayford Focuser
CGEM Hypertuned by Deep Space Products
Quote:I don't worry about all these so-called "comparisons" and just worry about getting out to actually use all this equipment that I have acquired over the years. In the end, observing is the single more important thing to consider when it comes to this hobby.
SLAP Observer --- TMB130SS, SV102V(LOMO Lens), SV80ED Deluxe "The only thing necessary for the triumph of evil is for good men to do nothing." -- Edmund Burke. "People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." -- George Orwell "The measure of a man’s greatness is not determined by what he accomplishes for himself, but by what he accomplishes for others.” -- Some Bald Guy
Happy owner of-- A Mag 1, 12.5 inch Porta Ball A Dual Axis Equatorial Platform A PST Double Stack
Quote:Quote:I don't worry about all these so-called "comparisons" and just worry about getting out to actually use all this equipment that I have acquired over the years. In the end, observing is the single more important thing to consider when it comes to this hobby. I have found that in planetary observing, hours at the EP will do more to improve your ability to observe small details than a new scope design or EP (unless you jump from a really small scope to a really big one). DSO's I can't comment on since I don't chase those. Observe with what you have and don't sweat the "is so-and-so better than so-and-so" comparisons.
Quote: The image through the unobstructed refractor is just so darned clean. You can also easily max-out the exit pupil without having to dodge around the shadow of the secondary.
Quote: Refractors give refractor like images, and reflectors reflector like images, and so on.
1st Caveman Award!Maynard Clark 8" f/8The Horsetrail Cave 12.5" f/7.51975 Cave 8" f/7 Lightweight Deluxe1972 Cave 8" f/4.5 RFT DeluxeCriterion RV-6Logitech HD C615 Webcam for Imaging
Quote:Wait a minute! Who has a 12.5" APO?
Quote: Quote:And comparing a large Newt to a small APO is comparing apples to oranges. Maybe comparing apples to peas? Jon
Joseph Cannavo FrontCollimation 16" F5 Teeter Dob Driver with novel azimuth friction clutch, and axial (rotating) electrical connection. Tom Osypowski equatorial platform 10" F5 Lightbridge Mid 70's RV-6 4" Orion 100mm ED Mr Keeyoots (My Cat).
Ed Jones ........... The best data is an interferogram, the best analysis is from an honest optician.
Quote:If it was April 1st again I might have the courage to goto the refractor forum and start a "Does your refractor give reflector like images?" thread.
Money can't buy happiness, but it sure makes living with misery a lot easier!