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meteorite
Reged: 01/28/06
Posts: 330
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Hello Everyone,
I currently use a very nice 6 inch f/8 reflector for lunar and planetary observing. It is also a great scope for double stars and the brighter DSO objects. I really like this scope, for various reasons.
I have been considering purchasing a 120 mm Skywatcher ED, refractor to basically replace my 6 inch reflector. For only $1500.00, the Skywatcher comes with an RACI finder, rings, 2 inch crayford focuser and dovetail (as well as two eyepieces). This is a really good deal, IMHO.
I am thinking the refractor would give nice contrast with very pinpoint stars (which is what I like)
I would appreciate opinions on whether the refractor would provide a more pleasing view via for example, better resolution, quicker cooldown time, more contrast than the reflector, etc.
I realize only I can decide if the refractor is right for me; just seeking others opinions. Concerning my viewing habits, I place quality of views over quantity. For me aperture does not always rule. I am not interested in AP, just visual.
I also realize I am asking this in teh Refractor forum so opinions may be somewhat biased 
Thanks everyone.
-Wal
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watcher
sage
Reged: 11/21/07
Posts: 492
Loc: NJ
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Personally,I wouldn't hesitate. I was a one scope man from 1987 until 3 years ago. I had a Celestron super C8 of average optical quality. It fell into disrepair a couple years before I got back into the hobby, so my comparison isn't a side by side,but the 120mm achro I got gives up very little if anything to the 8" for planetary and lunar. The rest of the sky is purely the domain of the refractor. The views are really something that the SCT was incapable of. I have to believe that going from a 6" reflector to a 120ED would be even more rewarding. To top it all off, you'll finally be looking into the right end of the telescope!
Joe
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(quote)"That does it! Next Big Bang, someone has got to rethink this gettin' old business!" Joe Daugert
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IM715 Mak Cass
1986 Celestron c-8 (retired)
Celestron Omni XLT 120
TMB 80SS on a Celestron SLT mount
AT 80ED
Celestron Astromaster 70 AZ
Vixen GP2 mount on Omni XLT tripod (driven by iOptron GOTO Nova)
Meade 16x50 binoculars
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DLB242
scholastic sledgehammer
Reged: 07/29/08
Posts: 860
Loc: Pen Argyl, PA
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Quote:
Hello Everyone,
I currently use a very nice 6 inch f/8 reflector for lunar and planetary observing. It is also a great scope for double stars and the brighter DSO objects. I really like this scope, for various reasons.
I have been considering purchasing a 120 mm Skywatcher ED, refractor to basically replace my 6 inch reflector. For only $1500.00, the Skywatcher comes with an RACI finder, rings, 2 inch crayford focuser and dovetail (as well as two eyepieces). This is a really good deal, IMHO.
I am thinking the refractor would give nice contrast with very pinpoint stars (which is what I like)
I would appreciate opinions on whether the refractor would provide a more pleasing view via for example, better resolution, quicker cooldown time, more contrast than the reflector, etc.
I realize only I can decide if the refractor is right for me; just seeking others opinions. Concerning my viewing habits, I place quality of views over quantity. For me aperture does not always rule. I am not interested in AP, just visual.
I also realize I am asking this in teh Refractor forum so opinions may be somewhat biased
Thanks everyone.
-Wal
The What kind of mount do you have for the 6" f/8 Reflector?
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David B
10" f/5 DOB
Celestron C8
6" f/8 DOB
Antares 1529 6" f/6.5 MoonLite Focuser
Orion 130ST f/5 Reflector 2" GSO Crayford
Stellarvue SV115EDT
Stellarvue SV102BV f/8.7 LOMO Doublet APO
Stellarvue SV90T f/7 Fluorite
Synta ST80
Stellarvue SV70ED
Stellarvue SV50 Little Rascal
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drshr
professor emeritus
Reged: 06/09/08
Posts: 745
Loc: Darwin, Australia
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I think you will find that the 120ED is better at just about everything, esp if your mirror coating is a little past its best.
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Doc
14" F5 DOB.
APM 8" F6 Achro.
ISTAR 152mm F10 Achro.(Building)
APM 105mm F6.2 CF APO.
120/F8.3
150/F5
80/F6.25ED
25x100 Binos.
All men are frauds. The only difference between them is that some admit it. I myself deny it.
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meteorite
Reged: 01/28/06
Posts: 330
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Thanks for the comments.
David, the 6 inch Reflector is on a plain vanilla dob mount.
-Walt
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RAKing
Carpal Tunnel
Reged: 12/28/07
Posts: 2522
Loc: West of the D.C. Nebula
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Your 6 inch Newt is a very nice instrument, but with the typical 20 - 22 percent CO it won't have any better contrast than a 120mm refractor anyway. So why not go for the better optics and totally clear aperture. I have a Newt, but it collects dust in the closet. I hate to fiddle with collimation and like the views better through the refractor.
You will need a mount to go along with your new tool - and it could be anything from a simple alt-az push along (like your Dob) to a GEM w/Goto.
The 120mm refractor is a very nice size - small enough and light enough to be Grab and Go for many, yet big enough to pull in a nice array of objects.
My .02,
Ron
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Time spent looking at the stars is added to your life.
Favorite Stuff: Astro-Physics, Baader, Celestron, Pentax, Takahashi, Televue, Zeiss, and .....
a beautiful wife - plus two furry cats who rule the world! 
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Lane
Carpal Tunnel
Reged: 11/19/07
Posts: 1682
Loc: Frisco, Texas
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Most people seem to feel that a refractor has about a 1.5" advantage over a dob. So a 4.7" refractor should be a little better than the 6" dob.
However you do lose resolution because that is based on the width of the main objective. So the dob will still split doubles better and show more stars in the core of a globular. Although they might be prettier in the refractor.
You lose a lot of light gathering ability because that depends on surface area and the dob has 62% more surface than that refractor. And whether the dob has an old mediocre mirror or a great mirror has very little to do with that value. So you will be able to see very faint things with the dob that will not be visible with the refractor.
Contrast is where the refractor excels, the central obstruction even a small one does reduce contrast. And contrast means you see the faint details better. So the bands on Jupiter will be sharper and contain more detail in the refractor and you will be more likely to see details in a faint galaxy as well.
So overall you will probably like a 4.7" refractor better than a 6" dob or a 6" sct.
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Mounts: CGEM, ORION SIRIUS, AT Voyager/jmi motorized
SCTs: C6, C8, C9.25, C11,
Refractors: TV Pronto, Orion ED80, AT106
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Luigi
Postmaster
Reged: 07/03/07
Posts: 5272
Loc: MA
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Ask this question in the reflector forum to get a "fair and balanced" perspective.
A 6" f/8 with a ~20% CO (1.2") can be an outstanding planetary scope. IMO, the 120ED, though a great scope (I have an EON120), would not be any better, assuming your 6" is decent one. There are pros and cons of size, weight, collimating, equilibration, viewing position etc., but at the eyepiece, you'd be hard pressed to see any difference and could just as well find the 6" Newt to be slightly superior. The place where refractors really shine is in lower power wide FOVs.
If you want an excellent refractor, by all means get the 120ED. It's an outstanding scope and value. Just realize the views won't be substantially different from what you're getting with your Newt.
Noted astrophotographer Damian Peach's website has an excellent page that illustrates, through simulations, the relative effects of varying aperture, % obstruction, optical quality etc.. It's quite illuminating.
Edited by Luigi (11/01/09 10:32 AM)
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Ennis
sage
Reged: 09/11/06
Posts: 412
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I recently purchased a Sky-Watcher Pro 120ED, and, contrary to the Sky-Watcher website, the telescope does not come with a right-angle, correct-image (RACI) finder (apparently, it originally did come with such a finder). Nor does it come with two long eye relief eyepieces. The telescope does come with a very nice "regular" finder and two average Chinese eyepieces, however, and a decent 2" diagonal. Sky-Watcher really needs to update its website. Having said all that, I still love my 120ED and recommend it. I actually prefer its mechanics over the EON 120.
Ennis
P.S. If you do get a Sky-Watcher Pro 120ED, I recommend that you also get a Scope Stuff 2" compression-ring visual back. It's a very nice upgrade to the 120ED and fits perfectly.
Edited by Ennis (11/01/09 10:14 AM)
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cuzimthedad
Just Be Cuz
Reged: 04/09/06
Posts: 3855
Loc: Sonoma, Northern California
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Based upon what you have stated about your observing habits and likes, I would say you are probably making the right choice. With that said, I am finding the better I get at collimating my dob, the more apoish views of stars I am seeing and I can't see much of a difference between it and my TV102 on them. However, I love all three of my scopes and have no bias for any of them. They all serve a purpose so I feel I can say, unbiased mind you  , that you should go for the 120ED and enjoy what it shows you.
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Dan
20" f/5 Obsession
Antares 1529
Various Naglers, Ethos, UO Orthos
Gone but not forgotten: Meade 5K UWAs & Plossls, WO UWANs, TV Plossls & T6 Naglers, Tak LEs, 13 & 17 Ethos, Vixen LVWs, Orion Stratus, Meade 12" LX200R, TV Genesis and TV102, Meade AR6, WO 80SD. All these helped to get me to what I own today.
The Off Fisher Lane Irregulars
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4263
Loc: S. Philadelphia, PA
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I use my 120ED more than my 12" dob for viewing the planets and the moon at high mags because of its tracking, rapid cool down time, lack of set-up and unbeatable contrast. It's a great scope! - j
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Fight indignorance!
120ED, 12" f/5 Green Goblin, 6" f/5 Eero2, 4.5" f/8 PortaBowl, 8" f/5 Big Red Ed.
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
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mathteacher
Carpal Tunnel
Reged: 05/13/07
Posts: 2477
Loc: Oakland, CA
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The 6 f/8 reflector is a venerable design. I think a good 120ED will be a keeper for life.
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Regards, Mr. Wang . . . . . . . Images and Gear. . . . . . . Let's Go Observing
CR 150-HD - The Hammer, Vixen ED100sf - The Skipper, Orion ST80 - The Pug
Join the International Dark Sky Association
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moonnerd
member
Reged: 12/18/08
Posts: 47
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Quote:
Noted astrophotographer Damian Peach's website has an excellent page that illustrates, through simulations, the relative effects of varying aperture, % obstruction, optical quality etc.. It's quite illuminating.
I don't want to hijack this thread, but this seems like a good place to talk about the wonderful link Luigi pointed us to. Are the conclusions on Damien's page basically what you find in real life?
If so, from comparing the photos in Damien's conclusion, it seems that the key hurdles to overcome are having optics at 1/4 wave or better, and an obstruction at 35% or less. After that, the main issue is aperture, assuming you'e comparing two equally good samples. Is that a fair interpretation?
Thanks,
rob
In that case, Wal (original poster) might be better off keeping his reflector unless it is too difficult to set up
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wfj
sage
Reged: 01/10/08
Posts: 280
Loc: California, Santa Cruz County
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Boils down to the scope that's used most.
For a while I'd use my refractors - long and short - the most. Then my cats - SCT's and MCT's. Then my newts - big, small, and long/short. I even set up pairs of them and did comparatives.
It all boiled down to "lazy" or "industrious" observation. If I was being lazy, the refractors got used more. If industrious, a larger newt got used the most.
On my logged observations, the vast (5x) majority were with a 10" newt - if I was being lazy with a refractor, I didn't log them, nor did I see anything new (other than comets). For a while I used my refractors for doubles exclusively, but when I got obsessive with finding/eliminating optical flaws in my newts (and lowering the CO to well under 20%) I no longer saw the point after A|B tests. Ditched all my long refractors. Kept one long newt - a 6" f/8.3.
I typically use short refractors for widest field views of subtle objects in dark sky, where contrast really matters - nothing beats them for this. In a pinch it's quite good past 400x with little CA. Shoot doubles with my newts, and have no complaints with the long newt - its a fantastically versatile scope which can be used on just about anything.
But when I need to check out an object being talked about, I pick the 10" newt for no muss no fuss show me the damn thing - it stands out so I find it quick in a 2 dg FOV. Keep it in a Rubbermaid storage container outside with a large desiccant = always cold and setup/teardown in two minutes.
Which is why the number of log entries are so, so high. Even when I'm resistant to doing so.
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Fomalhaut
sage
Reged: 08/16/08
Posts: 403
Loc: Switzerland
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Even if you'd compare to a 4-inch Apo:
Though a 6-inch Newtonian with minimized obstruction indeed CAN slightly (!) outperform a 4-inch-Apo on planets, the sum of the 4-inch-Apo's overall attributes excels the ones of the 6-inch-Newtonian:
Lesser susceptibility to decollimation, tube seeing/ground seeing, stray light (=> faint low contrast objects); more useful FOV, better in photographical applications...
Even more so is this the case if you compare the 6-inch-Newtonian to a 120mm-ED (which, by the way, can not be called a true Apo if it's not a triplet, but nevertheless - if it is a decent one - will certainly not be second to any 6-inch-Newtonian, neither on Jupiter's surface nor on any other target...).
I personally would not hesitate to choose, say a Tak TSA-120 (ED-triplet) over any 6-inch Newtonian in the world!
Chris
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Currently:
Tak FS-60c
Tak FCT-100/640 on Tak EM-10
Tak Mewlon-180 exchangeable on same
IntesMicro-M500
Zeiss 7X42-T*P-Dialyt
Nikon 18x70 Binoculars with circular eyecups
Coronado Maxscope 40
Edited by Fomalhaut (11/02/09 12:35 PM)
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roadi
professor emeritus
Reged: 08/18/07
Posts: 652
Loc: Denmark
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Quote:
Ask this question in the reflector forum to get a "fair and balanced" perspective.
A 6" f/8 with a ~20% CO (1.2") can be an outstanding planetary scope. IMO, the 120ED, though a great scope (I have an EON120), would not be any better, assuming your 6" is decent one.
I fully agree..
I once had an excellent 6" f8 planetary Newton, made by a company on the demand of a planetary scope. It had a 1" secondary, thin spider vanes (0.3mm) and a 200mm diam tube made of some synthetic materiel.. the optics was simply excellent but I didn't ask that time wich brand the mirrors were.. He was a meade dealer though!
It easily beated my 4" f15 Jaeger achromat on all objects especially Jupiter both resolution and contrast, and the 4" jaeger was/is no slough either just about equal an excellent 4" Apo on planetary observation.
I'm pretty sure that a well made 6" f8 planetary Newton (Right tube and about 16% CO) with excellent mirrors will be right up to any 120mm Apo, be it a triplet or doublet of any brand. Probably slight better!
I think it will boil down to wether one likes the design/look.. Newton vs Refractor design but in optical performance in the field the well made 6" f8 reflector won't take a second place to any 4-5 Apo but pretty sure the opposide way around.
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Regards Rodi
60mm Polarex, Sky90, µ210, SKW150 Binoscope
Vixen GpDx, Astro5, LX200
Modified Baader/Celestron Binoviewer.
Panoptics, Tak LE's, Baader Ortho's, Antares Erfle's
Couple of diagonals..
Edited by roadi (11/02/09 06:38 AM)
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wfj
sage
Reged: 01/10/08
Posts: 280
Loc: California, Santa Cruz County
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Quote:
I personally would not hesitate to choose, say a Tak TSA-120 (ED-triplet) over any 6-inch Newtonian in the world!
Chris
Once I would have agreed with you Chris - I have looked through that Tak too. No longer. Do anything with high regard for quality and you get similar results. Even APO's have limits one is wise to respect.
My point is in regards to quality always trumping in minimalistic optics.
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Fomalhaut
sage
Reged: 08/16/08
Posts: 403
Loc: Switzerland
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Quote:
Quote:
I personally would not hesitate to choose, say a Tak TSA-120 (ED-triplet) over any 6-inch Newtonian in the world!
Chris
Once I would have agreed with you Chris - I have looked through that Tak, too...
=> You have already looked  through one of those Tak TSA-120s???!
Wonderful, so you were one of the first! - Please tell the rest of that story: What have you seen? 
Chris
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Currently:
Tak FS-60c
Tak FCT-100/640 on Tak EM-10
Tak Mewlon-180 exchangeable on same
IntesMicro-M500
Zeiss 7X42-T*P-Dialyt
Nikon 18x70 Binoculars with circular eyecups
Coronado Maxscope 40
Edited by Fomalhaut (11/02/09 03:10 PM)
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Eddgie
Post Laureate
Reged: 02/01/06
Posts: 3279
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I personally don't think you will see much difference on the planets or moon assuming that the optics of your reflector are decent.
The additional 1.25" of aperture of the reflector is going to negate almost all of the contrast loss imposed by the secondary and spider, and the extra brightness in the 6" is enough to notice at the eyepeice on deep sky and on planets.
If your ultimate interest is in planetary observing, I would recommend that you go to a bigger, higher quality reflector like an 8" f/6. Put it on a tracking platform if you need tracking and you can still come out cheaper than a 120ED scope on a decent mount.
Small refractors make WONDERFUL planetary scopes when compared to small reflectors, but it is hard to beat good quality aperture, and it is VERY hard to be LOTS of aperture. Anyone that has ever seen Jupiter in an 8" Portaball or 7" Starmaster will tell you that there aren't to many refractors made that can provide BETTER views.
A 120mm ED scope may not actually provide ANY IMPROVEMENT in planetery performance over your current scope unless your current scope has poor optics. If it is a Vixen or similar quality reflector, don't look for any "OMG LOOK WHAT I HAVE BEEN MISSING!" moments, because there won't be any. If the quality is not very good, then a 120mm ED scope may offer a SMALL amount of improvement.
I have owned a variety of small refractors up to 6", and a good 8" f/6 reflector with high quality optics and 20% secondary would make a better planetary scope than any of them (perhaps includeing the Astro-Physics 6" I own).'
Go bigger if planetary is your passion. Get a high quality 8" f/6 and learn to be patient at the eyepieces, and you will see more than any 5" APO made today.
I like the 5" refractor range of telescopes because of their flexibility, but I do 100% of my planetary viewing with large reflectors (A CAT at that!). I don't even bother aiming my 4" refractor at the planets anymore because they just don't really provide much in the way of serious planetary observing detail and a 5" is not much better. Even a 6" refractor is only ok for planets.
Good luck. Enjoy your 120ED if you get it. They are nice all around telescopes.
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Celestron C14, CGE (Big Al)
Astro-Physics 6" f/8 (Buffy)
Celestron EdgeHD C8 (Lil' Eddgie)
Celestron C5 (Tiny Tiger)
Vixen Ed100sf
The night sky is my mistress. She seduces me away from all other lovers.
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AlienRatDog
Pooh-Bah
Reged: 07/15/05
Posts: 1221
Loc: Ann Arbor
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How do you think a C9.25 would do against a 127mm APO??
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Abe -- the poor PhD student
-----------------------------------------
12" LX200GPS-SMT w/UHTC
Celestron CPC800XLT
I guess I am a CAT man again..
Nagler 31mm, 17mm, 13mm, 12mm, 9mm, 2.5x Powermate
Explore Scientific 6.7mm 82deg eyepiece
12X50 Binoculars
Understanding wife
One beautiful daughter, Emma-Rose (born 7-29-2009)
Twin boys (cats), half Persian/half Alley Cat but all Vermin!
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