Orion xx14g Dob CPC 1100 w/Skywatcher 80ED piggybacked Coronado PST TMB 92L refractor AT Voyager mount Nexstar 6/8 mount Denk Big Easy binoviewers Oodles of eyepieces and other optical gadgets Past scopes Meade 8" reflector and 8" SCT
Quote:Hi.I am soon going to buy a 12" newt (XT12g) which has focal ratio 4.9.I want to buy a set of eyepieces "once", i.e. "do it right the first time".(Haha, has that ever happened?)ONE burning question is "will I need a coma corrector?"Or, if I buy superior eyepieces, will I be fine without one?(Don't hesitate to recommend particular EPs that would do the trick)Follow up question: WHICH coma corrector?Paracorr VERY expensive, Baader, GSO, Highpoint offerings much less.Should I spend triple the price for the paracorr?Thanks so much to anyone willing to share their expertise.Dave
My eyepieces are made from the waste product of exploding stars. 10XTi 102XLT ST80A(2" Focuser) XW: All; XO: 2.58 Televue: Naglers-T1 Smoothside-full set, 17T4,12T4,Ethos 17,4.7; plossels-40,32,20,17,&7.4mm; Pans-22,24mm; Delos-6,8,12,17.3mm ES100: 5.5,9*,14,20 ES82: full set ES68: 16,20,24,34 NLV: 5,9,10,15 Ortho: HD-7,9; OPS-9,12 Meade RG 7mm Other: Pentax 12.5K(.965), 10mm Parks Zoom: Nag3-6 *=on b/o DAS Dark Site
François C8 f/10, lunt 102 mm f/7 ED. SkyWatcher 12" f/5. pentax XW 40, 30,10 delos 14, 8, 6, 4.5. Vixen lvw 22 Brandon 12, 8 TV 2x barlow Closer and closer to the ideal eyepiece collection, but never reaching perfection
Quote:All good summaries above. I had the same question for my f5. At the end of the day you're just going to need to try it out. Borrow one if you can. If not, just get ready to jump on the used market for a type I - they sell quickly. Worst case you can resell it for little or no loss.For me, at f5 a paracorr is worth it.
Rob 18" f/4.3 Starmaster 8" Meade LX200 Classic Celestron 15x70 Skymaster Binoculars
Quote:Strictly speaking, they are not required but they do enhance the views, pinpoint stars edge to edge when you're looking at the Double Cluster or Pleiades adds to the "spacewalk experience" ultra-wide angle eyepieces offer.
Quote:After several years of tollerating coma in my Dob, I too am considering cleaning up my act and opting for a parracorr.Coma bothered me last night. First time ever that I found myself getting annoyed. I was viewing the BeeHive cluster in the wee hours.So at f/4.5, it can be bothersome.jake
Quote: I just decided to swing for the Feather Touch with the built in coma corrector. Not the one on Teeter's site which is a regular FT with the corrector as a add on which ups the cost quite a bit.. The one on FT's site goes for $860 with base. I was going to get the Moonlight so my extra expense is around $694. David
Orion XT12g 12" f/4.92 GoTo Dob Orion 9x50 RACI - Green Laser Pointer Orion 4.5" f/4 EP: ES82 30mm, ES68 24mm EP: Hyperion 21, 17, 13, 10, 8, 5mm Various filters, including Skyglow, UHC, O-III Celestron Ultima 2x Barlow Celestron 12x80 binoculars & mount
Quote:Am I the only one with an XT12g (f/4.92) who doesn't see a paracorr as necessary or worth the money?
Scope: Zhumell 10 inch Dobsonian w/ Antares 80mm finder EP: Meade 5000 HD60 set; Meade 5000 UWA 24mm; Meade 4000 6.7, 9.7, 12, 15; UO Konig "Zebra" 24mm; Celestron "Silvertop" 26mm; Agena 66 UltraWide 6, 20mm; Accessories: GSO coma corrector; Zhumell 2inch barlow; Meade, Celestron and GSO color filters; Lumicon UHC, OIII & DeepSky 1.25, Lumicon 2inch DeepSky.
Quote:Quote:After several years of tollerating coma in my Dob, I too am considering cleaning up my act and opting for a parracorr.Coma bothered me last night. First time ever that I found myself getting annoyed. I was viewing the BeeHive cluster in the wee hours.So at f/4.5, it can be bothersome.jake I notice that folks pretty much equate "coma corrector" with "paracor".The coma correctors from Baader, Highpoint, GSO, are so much cheaper, but I'm not finding much in the way of reviews. Surely Baader makes a quality product?The Baader appears to be the only one that has no magnification.Is anyone having success with any of these more economical alternatives?
Quote:A coma corrector ISN'T absolutely necessary...
Quote: There's only one tell tale sign of coma and that is the little comet tales that appear radiating out from the centre around the edge of the FOV.
Home made 16" f5 Terry Ostahowski optics - ArgoNavis/ServoCAT ES 30 mm, Ethos 21, 13 and 10 mm Paracorr II Antares Barlow 2" 1.6X 2" DGM NPB (UHC) filter 2" Catseye Cheshire/Sight tube 2" Howie Glatter laser + Tublug
Quote:Well I had my maiden outing with a new xx14g last night (f/4.6) and I tested it without the AT coma corrector first to see how the CC altered or otherwise improved views. With it installed coma declined at the edges of the field by about 90 percent. It definitely made view of wide field objects more enjoyable and aesthetically pleasing. I would be somewhat less inclined to invest in the Paracorr which costs about three times as much. I find the AT model, which I imagine is pretty much identical to the GSO one, to be quite adequate for my needs. But I also find on first impression that it is a worthy visual upgrade, not necessary and quite desirable.
Quote:...With it installed coma declined at the edges of the field by about 90 percent. It definitely made view of wide field objects more enjoyable and aesthetically pleasing...
Quote: This mirrors my experience. This Roger Ceralioli design works well and needs no turntable with a sensible choice of eyepieces. I currently use my scopes with ES82s, ES68s and a Baader Hyperion Aspheric.
Quote: BUT where it can become an issue though with visual is using the ultra, ultra wide eyepieces, 100deg +. Here, the increased magification afforded will increase the apparent size of the aberration. Coma in a 21mm 100deg EP will be more significant than in my 34mm 68deg eyepiece by virtue of the increased magnification even though the TFOV is just about identical.
Quote: For telescopes with coma or field curvaturre, a Panoptic (or similar high quality 68 degree wide field eyepiece) with the same size true field as a Nagler or Ethos will magnify the abberated blur so much less that it becomes very hard to see.
Quote:Once of the primary advantages of a big Newtonian reflector is that it can easily provide a big exit pupil. A big exit pupil makes extended objects appear brighter.
Quote: In other words, given two EPs of similar quality, with the same FL (and magnification), a 68° EP sees the best part of the available FOV. An 82° EP would see that same FOV,
Quote:I was not aware of this. That makes the exit pupil an even more important consideration in choosing EPs.Is the perceived brightness directly proportional to the square of the exit pupil?Is it just more area of the eye being "lit up", or what?
Quote:And deep sky observing is very much about exit pupil. Lots of people using small scopes routinely see "Difficult" targets like the Whirlpool and Veil nebula because they know that you can see them just as easily in a 4" refractor as you can in a 12" reflector if you use a 6mm Exit Pupiil in both scopes.
Quote:The difference in image scale is rather minor. So is the difference in magnification. But the difference may be enough that the coma is not as objectionable or even hard to see when using Panoptics, making him less likely to need a Paracorr.