Barnard Astronomical Society
Celestron 8SE Dobstuff 13.1": Swayze refigured Coulter mirror, 6 pt mirror cell (2 pt edge support) and CF focuser board made by me StarBlast 4.5 ST80/PortaMount II Zhumell 20x80/Oberwerk 15x70 on a Seronik-style tripod boom mount Hubble Optics 18 inch F/4 mirror.
Quote:I haven't used any of those 3 telescopes, but I would go with the Parks as well. Aperture is king on planets, contrary to what some may tell you. I had an FS-102 and I never found it be a great planetary scope. Don't get me wrong, it provided aesthetically pleasing images but the detail was not there. And that's a world class 4-inch APO. I don't know how the Mak-Cass will stack up against the Parks. F/8 is nice for a Newtonian, generous diffraction-limited field.
18" f/4.2 homebuilt truss 12.5" f/6 hybrid tube dob
Quote:I agree. I also think that 6 inches is where it just starts to get interesting. I had a 6-inch Intes mak that was wonderful on Saturn, perhaps less so on Jupiter: that is, fine, high-contrast detail was great, whereas low-contrast stuff was harmed a bit by the CO. If you can find an 8-inch f/6 Newt OTA for your mount, one with a good mirror, I would go with that, provided you have a way to rotate the tube. And don't be afraid to buy used.
Quote:Ed D, that's an interesting idea. I haven't actually found pricing for such a thing except getting a re-coat job done which was under $100 for an 8" I think... It seems the practical solution is to get the newt out and do some tests before making any purchases. I've been manly concentrated in using imaging equipment thus far after a bad experience with an ES AR152 refractor and selling my Z12 dob. I thank you for your input, that is also an excellent option although I'm still leaning towards a longer focus instrument. I will definitely make note of that.
Quote: I see that Gray/Graham already has an 8 inch F/5 Newtonian as well as an Atlas Mount. I suspect that this is at least as good and probably a better planetary scope than any of the three smaller scopes. I can see two ways to proceed. First would be a longer focal length 8 inch such as George suggests. The second would be to make sure the 8 inch F/5 has good mirrors, have both tested and reworked/replaced as needed.The Skywatcher 100mm F/9 ED has the virtue that it will cool down much quicker than the others...Besides, everyone needs a decent 4 inch refractor, that's just how life is.Jon Isaacs
Quote:If you are really, really looking for a planet-optimized telescope, and are willing to go the full $1000, then you might take a look at this:http://www.optcorp.com/product.aspx?pid=67-12025It is an 8" F/9 with a 15.6% central obstruction.
Jeff Morgan - Wile E. Coyote School of Telescope Making
Quote: I will need to find a supplier for that accessory (on the cheap if possible).
Quote:I gather from what you say that Parks is no longer in business, even though their site is up and current? Now then it looks as if I should just upgrade my newt with fans, flocking, and I'm wondering what you guys think of a curved spider? 3 or 4 vane. I was thinking 3, for my 8" even though they are expensive at $94 from Jim at Scopestuff. I'm also wondering if I should replace the secondary or keep it. What would you suggest I upgrade my scope with altogether, for optimizing it for planets is a better question of questions. Or would another scope be a better option? Thank you Starman
ROR Observatory Levenhuk 8" carbon fiber RC, Astro Physics CCDT67 Astro-Tech AT8IN w/Moonlite, Baader Mark III MPCC Levenhuk 80mm triplet, Astro Tech 0.8X reducer/flattener Celestron CGEM DX w/HyperTune STF-8300M SX 7 position 36mm CFW Astrodon 5nm H-alpha Little Piney Observatory
If you upgrade the scope but keep it possible to use your mounts, an 8" f/6-f/7 would still work and the secondary would be a little smaller.
An f/9 would be getting somewhat heavy and too big a wind sail, not to mention having an inconvenient eyepiece position for comfortable viewing.
Frankly, by today's standards, f/5 is long. Imaging scopes are typically f/3-f/4.
And, as long as your scope tracks, you'll not need a coma corrector at f/5.
Quote: I do have a laser and a Cheshire but maybe I should look into better tools.