You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar

Observing >> Double Star Observing Previous   Index   Next   Threaded

Pages: 1 | 2 | 3 | 4 | (show all) Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: Daniel Mounsey]       #5508104 - 11/07/12 09:50 AM Attachment (56 downloads) Edit   Reply   Quote Quick Reply   And more often, this is what the refractor will look like. Post Extras:       Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: Daniel Mounsey]       #5508152 - 11/07/12 10:25 AM Attachment (41 downloads) Edit   Reply   Quote Quick Reply   The solution is an aperture mask, which will greatly clean things up to make the image look like #2. Two important things will happen though. 1) reduced angular resolution. 2) light loss for seeing fainter stars. The solution? Make a list of double stars that are within the power range of the aperture and enjoy, problem solved. Sure, there will be some nights where you'll wish you had a bit extra, but that mask is a great solution. Post Extras:       dpwoos Pooh-Bah Reged: 10/18/06 Re: refractor best for doubles? [Re: Daniel Mounsey]       #5526166 - 11/18/12 01:38 PM Edit   Reply   Quote Quick Reply   Here in Vermont (not thought to have very good seeing) I regularly get clean, beautiful splits of iota Cass in my homemade 10" f/6 dob at 120X. I accept that a top-flight refractor can split doubles at lower magnifications than a significantly larger reflector, but it ain't a huge difference - more like 20-30% less mag at the most. I think that any 10" reflector that can't keep up with a smaller refractor within that range has some problem(s). Edited by dpwoos (11/18/12 01:40 PM) Post Extras:       Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: dpwoos]       #5528741 - 11/19/12 08:28 PM Edit   Reply   Quote Quick Reply   Your point is well taken. Actually what the images mainly imply are thermals that many amateurs encounter. I remember using my 14.5" dob(which I sold) on doubles with and without the off axis mask at a regular event which rarely encountered good seeing. The results with the smaller off axis aperture mask were much better. Where the aperture comes in handy though are on fainter doubles and tighter doubles but that's only if the circumstances allowed. My 10" DK easily outperformed my 6" apo by splitting finer and tighter doubles, no if ands whats or bts about it. The general issue though is that aperture is over rated, mainly because the average observer will most likely adopt a reflective design. Because of the inherent issues they encounter, it requires special attention that most observers would not be aware of in fact I know several veteran observers here on CN who still don't even know. Post Extras:       dpwoos Pooh-Bah Reged: 10/18/06 Re: refractor best for doubles? [Re: Daniel Mounsey]       #5529249 - 11/20/12 12:59 AM Edit   Reply   Quote Quick Reply   I know that my 10" dob is excellent, and yet I also know that it is not as up-to-snuff as a $4,000 apo. My collimation is imperfect, and my coatings are imperfect, and my thermal control is imperfect, and my stray light control is imperfect, and the larger exit pupil means that my imperfect eyesight also comes into play. However, I also know that the views of Jupiter that I had this evening surpass anything that a much smaller (but more perfect) apo can provide, and the fact that I can easily split 1 arcsecond doubles means that, in my mind, my homemade reflector is one heck of an instrument. I can live with the fact that the apo can split a 2 arcsecond double at 70x whereas my 10" requires 90x! Post Extras:       Asbytec Guy in a furry hat Reged: 08/08/07 Loc: La Union, PI Re: refractor best for doubles? [Re: dpwoos]       #5529288 - 11/20/12 01:44 AM Edit   Reply   Quote Quick Reply   Well, I promised Mike Cee I'd promote his 10" refractor as the best scope on doubles. Post Extras:       Ziggy943 Post Laureate Reged: 08/11/06 Loc: Utah Re: refractor best for doubles? [Re: mikey cee]       #5532093 - 11/21/12 11:51 AM Edit   Reply   Quote Quick Reply   Quote: I don't need perfect seeing to detect the dark space in 72 Pegasi.....but it sure would make a perty picture! Mike Awesome view of your scope. Post Extras:       Asbytec Guy in a furry hat Reged: 08/08/07 Loc: La Union, PI Re: refractor best for doubles? [Re: Ziggy943]       #5532135 - 11/21/12 12:14 PM Edit   Reply   Quote Quick Reply   Daniel, that's zeta Cancri. (Edit: just realized it even says so in the corner...LOL) More often than not, the obstructed views of zeta Cancri I get are more refractor like according to your image comparison. The difference you illustrate is a bit harsh toward obstructed scopes. I understand you were driving home a point, but that comparison is scary for reflector owners. The message is refractors are pretty, reflectors are UGLY. That's just too biased. No doubt refractors have a very aesthetic view and beautiful diffraction patterns. It's probably (and sadly) true many reflectors operating out there need proper collimation and cooling. But, that's no fault of a superb design. If the aperture debate is off the table, well the argument ends here. There are a lot of variables to cover, including the nature of seeing. I disagree the solution is to stop down the aperture and settle for a wider Dawes limit. However, doing so when conditions suggest it will help is fine. An aperture mask is a tool, not a solution. But an obstructed scope can put up nice images with nice diffraction patterns, too. Cooled and collimated, of course, as you correctly imply. And if so, they will look like your second image, more often than not. Edited by Asbytec (11/21/12 12:21 PM) Post Extras:       Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: Asbytec]       #5532976 - 11/21/12 09:27 PM Edit   Reply   Quote Quick Reply   Norme, after looking at it some more, I actually agree, it is a bit too harsh. Let me see if I can find something a bit more accurate. Thanks for mentioning this. I don't want to mislead anyone too much. Edited by Daniel Mounsey (11/21/12 09:35 PM) Post Extras:       Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: Daniel Mounsey]       #5533011 - 11/21/12 09:56 PM Attachment (25 downloads) Edit   Reply   Quote Quick Reply   How about this for on Albireo instead. Hard finding accurate images hmmm... Post Extras:       Asbytec Guy in a furry hat Reged: 08/08/07 Loc: La Union, PI Re: refractor best for doubles? [Re: Daniel Mounsey]       #5533031 - 11/21/12 10:11 PM Edit   Reply   Quote Quick Reply   LOL, Daniel. Spikes! Well, if a refractor was looking over a clothes line, eh? (Chuckling silently to myself.) Post Extras:       Daniel Mounsey Vendor - Vixen Optics Reged: 06/12/02 Re: refractor best for doubles? [Re: Asbytec]       #5533043 - 11/21/12 10:19 PM Edit   Reply   Quote Quick Reply   LOL!!! Maybe you could share something that gives an idea of the appearance in the eyepiece. The Albireo image is too saturated. Post Extras:       Asbytec Guy in a furry hat Reged: 08/08/07 Loc: La Union, PI Re: refractor best for doubles? [Re: Daniel Mounsey]       #5533055 - 11/21/12 10:32 PM Attachment (28 downloads) Edit   Reply   Quote Quick Reply   If you looking for something with spikes, I'd have to drop by the mall. Well, cooled and perfectly collimated and obstructed, maybe something like... Post Extras:       zvaragabor member Reged: 01/25/11 Re: refractor best for doubles? [Re: Asbytec]       #5546693 - 11/30/12 06:20 AM Edit   Reply   Quote Quick Reply   Do you think a 90/1000 refractor is good for double star observing? Post Extras:       azure1961p Postmaster Reged: 01/17/09 Loc: USA Re: refractor best for doubles? [Re: zvaragabor]       #5546733 - 11/30/12 07:30 AM Edit   Reply   Quote Quick Reply   A 90mm is fine and some folks are forever content and even prefer it over larger though obstructed telescopes. I prefer my 6 and 8 over a smaller refractor as the available list of doubles resolvable in both seperation and color is substantially longer. The bigger you go the less u have to pick and choose but those beautiful BRIGHT doubles can then appear blown out and glaring through bigger apertures. Just some thoughts. My 70mm is dandy on doubles but I prefer my 8". Pete Post Extras:       zvaragabor member Reged: 01/25/11 Re: refractor best for doubles? [Re: azure1961p]       #5546737 - 11/30/12 07:35 AM Edit   Reply   Quote Quick Reply   Thanks azure. Unfortunately 6" (and more) is out of my budget, and it even needs a larger mounting, which weighs and cost even more. I want a lightweight and low-budget scope. I even thought of a 4"/1000. Edited by zvaragabor (11/30/12 07:37 AM) Post Extras:       WRAK sage Reged: 02/18/12 Re: refractor best for doubles? [Re: zvaragabor]       #5546951 - 11/30/12 10:37 AM Edit   Reply   Quote Quick Reply   With a 4" refractor you have many 1000 interesting doubles within the range of your scope and it es very easy to use - certainly a good choice for DSO. Wilfried Post Extras:       azure1961p Postmaster Reged: 01/17/09 Loc: USA Re: refractor best for doubles? [Re: WRAK]       #5547003 - 11/30/12 11:25 AM Edit   Reply   Quote Quick Reply   Youmight find Orion's 6" f/8 reflector dob very budget friendly. Probably more affordable than the refractor. I appreciate your budget concerns. At anyrate either system well made is at least good. Pete Post Extras:       zvaragabor member Reged: 01/25/11 Re: refractor best for doubles? [Re: azure1961p]       #5547220 - 11/30/12 01:23 PM Edit   Reply   Quote Quick Reply   I own a 10" reflector dob, so a 90mm refractor would be a huge step back. But my dream is to observe doubles with a long focal length refractor. A refractor with aperture 90-100mm, and f/ratio f12-15 would be the best, but unfortunately it's a rarity in Hungary. The closest match is a Meade DS-90 (90/1000), a Soligor 3.7"/1000, or a Celestron 100/1000. All the tree are within budget, but the longest f/ratio is the meade. I know the bigger aperture means a slightly better resolution, but I symphatize with the meade. Post Extras:       azure1961p Postmaster Reged: 01/17/09 Loc: USA Re: refractor best for doubles? [Re: zvaragabor]       #5547663 - 11/30/12 06:47 PM Edit   Reply   Quote Quick Reply   In that case get the refractor by all means. It compliments what you have in the 10" and if ever you feel the need for more resolution reach for the ten. Both s opes would actually strike quite a fine balance. It IS fun going between my refractor and reflector. I thought you were looking for one to do it all. And a lot of folks who are seasoned observers actually are fine with four. Good luck with your choice. You were fine anyway I just thru in my two cents. Post Extras:       Pages: 1 | 2 | 3 | 4 | (show all)

Previous   Index   Next   Threaded

Extra information 3 registered and 2 anonymous users are browsing this forum. Moderator:  PJ Anway, RLTYS  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 5379 Jump to *Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Celestial Events*General Astronomy* -----   Beginners Forum   General Observing and Astronomy   Outreach   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning and Intermediate Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   NEO   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Speciality Forums* -----   Arizona Science and Astronomy Expo   NEAF (Northeast Astronomy Forum) and NEAIC (Northeast Astro Imaging Conference)   AstroArt   Astronomy Clubs and Star Parties   Astronomy Software & Computers   AstroWebsites   Science! Astronomy & Space Exploration, and Others   Space Rocks   Stellar Media*Swap and Shop* -----   Shop and Swap Audio Components*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements*International Year of Astronomy 2009 - Forums are now closed.* -----   IYA Archive Info

CN Forums Home