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Paul G
Post Laureate
Reged: 05/08/03
Loc: Freedonia
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5213650 - 05/09/12 12:09 PM
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As much as I really am taken with the idea of getting a 5" refractor, I just can't seem to pull the trigger.. I am having a hard time understanding why I shouldn't just get a smaller SCT like a 5" Celestron SCT OTA or something like that at a fraction of the price?
My big question is.. What does a refractor do for me that an SCT does not? I'm not into AP, so that's not a factor. It just seems that for the size/portability and most importnatly cost, an SCT wins every time. Refractors are cool, stylish, a lot of fun to use (a rifle to hunt the stars!), but that seems to me to be only minor reasons in their favor.
I am not going to shell out the kind of money needed to get a high-end refractor, so I am thinking the top of my scale would be an ES 127 CF to try to get the weight of the scope down a bit and use it with a midrange alt/az mount like the ES Twilight II mount. It's a beautiful scope, but when an equitable SCT costs far less... I mean, look at the Edge HD 8" OTA! It costs almost a thousand dollars (40%) less than a nice 5" refractor like the ES and weighs less. How can a 5" refractor compete with a 8" SCT if aperture always rules?
As much as I want a large refractor, I don't think I can justify it. My 90mm refractor is great for a grab and go and a lot of fun to use, but for pure viewing performance, I will always use my 8SE over it when I can. I'm thinking I should just get the Twilight II mount and use it with the 8SE OTA as a manual alt/az grab and go scope instead of a large refractor.
Go to a star party and observe with the size scopes you are considering. Aperture doesn't always rule, particularly on low contrast planetary detail.
Scopes are tools, each one excels at a different task. The best choice for deep sky isn't necessarily the best for planetary observing, etc.
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dajebriza
member
Reged: 01/15/12
Loc: Germany
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Re: Why a refractor over a larger SCT at less cost?
[Re: Paul G]
#5213795 - 05/09/12 01:25 PM
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Great advice everyone.. Refractors are awesome, but significantly more expensive.. I couldn't go for a low-cost Acro.. I would need an APO, which is why I was considering the ES 127 triplet... Its very tempting at $500 off right now, but I think the best advice to follow is to stick with my 8" SCT and smaller refractor and spend more time evaluating at star parties to reach my decision, not jump into it since it seems it is certainly not a resounding "yes! you MUST get the 5" refractor". A split chorus of yay vs. nay, especially in the refractor-centric forum tells me its not that critical a must have and the 8" SCT is a large enough light bucket to close the gap between the 5" APO for the time being.
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Mark Costello
Carpal Tunnel
Reged: 03/08/05
Loc: Matthews, NC, USA
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5213848 - 05/09/12 01:48 PM
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Great advice everyone.. Refractors are awesome, but significantly more expensive.. I couldn't go for a low-cost Acro.. I would need an APO, which is why I was considering the ES 127 triplet... Its very tempting at $500 off right now, but I think the best advice to follow is to stick with my 8" SCT and smaller refractor and spend more time evaluating at star parties to reach my decision, not jump into it since it seems it is certainly not a resounding "yes! you MUST get the 5" refractor". A split chorus of yay vs. nay, especially in the refractor-centric forum tells me its not that critical a must have and the 8" SCT is a large enough light bucket to close the gap between the 5" APO for the time being.
Hi dajebriza. If I read your post correctly, you're making a good move in going very slowly on this. My guess is that the ES127 apo will outclass the C5 in everything except for two areas: portability and ease of use (demand on mount, ease and rapidity of setup and teardown, etc.). Those two areas can be important to a lot of amateurs and it appears that they are important to you. It appears that you have two really nice and nicely complementary telescopes. If I had your lineup, I'd be moving really slowly on this ... and if I really wanted something between the SV90 apo and the C8, I'd probably go for a C6. Submitted FWIW, and all success in your choice....
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NHRob
Post Laureate
Reged: 08/27/04
Loc: New Hampshire
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Re: Why a refractor over a larger SCT at less cost?
[Re: Mark Costello]
#5213895 - 05/09/12 02:13 PM
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because SCTs are inherently evil and refractors are virtuous !
Apos, in particular, have been known to cure gout, hare-lip,
ED, and a host of embarassing skin conditions.
Rob
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George Methvin
Pooh-Bah
Reged: 01/30/06
Loc: Central Texas
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5213917 - 05/09/12 02:26 PM
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Daj I have own a 8,11,and 10 SCT and they were all very good scope. I always wanted a Apo refractor hearing so many refractor nuts swear by them. So not being rich I bought the Orion 120ed and it was one of my best ever buys very sharp love viewing throught it but no matter how you cut it is still just a 120mm telescope. Would I like a 130mm or 140mm or larger APO you bet, will I ever buy a 130mm or 140mm Apo not really just to costly and to little apature. If I had that much money to spend on a scope I would go with a frist class large Dob or a 14 in SCT. Sounds like you have two good scopes now, go to a few star partys and look through as many scopes as you can it may help you pick what you want. Clear Skys.
Meade 10 sct Classic
Orion 120mm ED refractor.
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gnowellsct
Postmaster
Reged: 06/24/09
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Re: Why a refractor over a larger SCT at less cost?
[Re: The Mekon]
#5214207 - 05/09/12 05:36 PM
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Aperture does not always rule. I have never seen an 8" SCT that can come close to the views that my 130 AP delivers. And that includes deep sky objects.
Well that's true. I would prefer my FS128 to a c8. But things start to get interesting with a 9.25 in terms of preferences. And the 9.25 is *still* a fraction of the price and has the additional merit of being available. One basis for the comparison is that the 5" apo and the 9.25 will both ride on the same mount.
What's really nice about the apo is the ability to go from the lowest power (typically in the low 20s) to a very high power (50x per inch or more) and have great performance. SCTs at 50x per inch can't really be evaluated because the long fl puts them out of range of most seeing. But they cannot deliver those wide field views.
They do lots of other things though. For me the equipoise point is between a 9.25 and a 5" apo.
A TEC 140 would add an argument for the apo, a tad more aperture at a size where that matters.
One argument for the SCT is that since it basically can be had for the price of two or three eyepieces used, you can buy it, use it, and continue saving money for the apo.
Then you might end up mounting them side by side. No loss there.... Greg N
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Joe Bergeron
Vendor - Space Art
Reged: 11/10/03
Loc: Upstate NY
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5214221 - 05/09/12 05:44 PM
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So just get what you want. Problem solved.
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Ennis
scholastic sledgehammer
Reged: 09/11/06
Loc: The Outer Limits
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Re: Why a refractor over a larger SCT at less cost?
[Re: NHRob]
#5214255 - 05/09/12 06:13 PM
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because SCTs are inherently evil and refractors are virtuous !
Apos, in particular, have been known to cure gout, hare-lip,
ED, and a host of embarassing skin conditions.
Rob
E.
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Starhawk
Post Laureate
Reged: 09/16/08
Loc: Tucson, Arizona
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Re: Why a refractor over a larger SCT at less cost?
[Re: Ennis]
#5214802 - 05/10/12 01:05 AM
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I always find myself torn between the C5 and C6. But the truth is, most of the other scopes have been accruing a lot more hangar time since the AP130 EDFGT showed up. The C8, C11, 80mm scopes- they just can't cover that range of magnifications. Typically the 130 will do whatever the atmosphere is up for.
But can I say "Go get something like that, now!"? It's a bit of money, mounting isn't trivial. Some people end up not getting into them, even after waiting 9 years. The AT130 should be available, and folks seem to love them. No matter what, the neighborhood around 5" seems to have quite a bit of magic available, do making the most of it is useful.
One of the best things about spending time with SCTs is it will teach you to make more of lower contrast images- which is a useful skill, later.
-Rich
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aa6ww
sage
Reged: 10/23/11
Loc: Sacramento, Calif.
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Re: Why a refractor over a larger SCT at less cost?
[Re: tomharri]
#5214845 - 05/10/12 02:13 AM
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Why a refractor? The quality of the view. For planetary use a refractor will out perform the average sct, newt. that is twice the diameter, 4" refr.ED better than 8"sct.
However for all round use on clusters and nebula, bigger is always better.
The basic achromat doesn't count, and high quality mirrors can approach APO performance at much lower price.
Honestly, the real bottom line is, if you can comfortably affort a high quality APO, you'd get a smaller one and a larger one, I mean like a tak, ap or tec. They would then be your high end optical instruments. Then you would just go for aperture, whether its a newt or sct. If you cant affort one of the high end scopes, then you have to make compromises based on how much you can spend. People say "APO Refractor-like" for a reason. Everything else is a compromise unless you just want raw light gathering, then you just get a big reflector. When you can afford.the best, you alway end up with a high end apo and a big reflector of some type... Period.
....Ralph
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CounterWeight
Postmaster
Reged: 10/05/08
Loc: Cloudyopolis, OR.
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Re: Why a refractor over a larger SCT at less cost?
[Re: aa6ww]
#5214880 - 05/10/12 03:23 AM
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i jumped from larger SCt types into refractors and a huge amount of why it made sense initially was my skies and typical viewing conditions here in the pacific northwest -oregon to be specific. When i got out to dark sites regularly with my large cat's it was just fantastic. But I do a majority of any astro stuff these days in my light polluted home turf. I really miss the light gathering of 11 and 12" on some objects - and will soon remedy that. But the always good views from my refractors make me want to hold on to them, never soft and always able to push to the limits of my local seeing without wondering if I'm off in collimation or mirror not cooled well... refractor = sharp and contrasty at what they pull in, always enjoyable fully to whatever your local seeing will permit.
I add another + to see what folks in your area are getting with what they use and what the tradeoffs are - your typical local seeing and it's limits are really most important to grasp.
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Maverick199
Postmaster
Reged: 02/27/11
Loc: India
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5214923 - 05/10/12 06:20 AM
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Surefire way for curing aperture fever is getting one of those Refractors.
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George N
Carpal Tunnel
Reged: 05/19/06
Loc: Binghamton & Indian Lake NY
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Re: Why a refractor over a larger SCT at less cost?
[Re: Maverick199]
#5215248 - 05/10/12 11:06 AM
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Surefire way for curing aperture fever is getting one of those Refractors.
I was considering a C-8 EdgeHD vs an ES127ED as a new addition to my scope collection. Note that, in addition to the scopes listed below, I have easy access to observatory-mounted 20-inch RC, C-14, and 6-inch A-P refractor.
I concluded that the 5-inch refractor would be more versatile, and would better meet my needs for a wide-field visual scope that would still do well on things like the moon and planets, and would also be a nice wide-field imager. After 2 years, with much chance to compare the refractor to C-8’s, I’m very happy with my decision, but I might have gone the other way if it were my only scope.
For the past 2 years I often set up the ES127ED and my Obsession 20 side-by-side for visual observing. At major star parties I end up with lines of 10 or more people wanting to look thru the big Dob while the refractor sits unused tracking on something like the North America Nebula, M-31, or a planet. I practically have to drag people over to look thru the 5-inch. Occasionally a “fractor nut” shows up and heads right to the little white tube.
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George N
Carpal Tunnel
Reged: 05/19/06
Loc: Binghamton & Indian Lake NY
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Re: Why a refractor over a larger SCT at less cost?
[Re: Joe Bergeron]
#5215266 - 05/10/12 11:12 AM
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So just get what you want. Problem solved.
My solution would be to get ‘um both!
Come to think of it, I need to get a SCT and a Mak so that I can’t be accused of bias in these CN discussions. I feel deprived with only an RC, APO, and 6, 8, and 20-inch Newts…… oh, wait, I forgot the 7x50 and 20x80 binos and my 50mm Galileoscope.
....just think what fun I'll have if it ever clears up! 
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: Why a refractor over a larger SCT at less cost?
[Re: dajebriza]
#5215311 - 05/10/12 11:38 AM
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My big question is.. What does a refractor do for me that an SCT does not? I'm not into AP, so that's not a factor. It just seems that for the size/portability and most importnatly cost, an SCT wins every time. Refractors are cool, stylish, a lot of fun to use (a rifle to hunt the stars!), but that seems to me to be only minor reasons in their favor.
To know why people pay big money for a refractor, you really have to look through the eyepiece, there is a perfection there that cannot be duplicated with an SCT.
As others have said, a C-5 is no match for a 5 inch apo, it has too many limitations...
As far as aperture "ruling", I have to disagree, there are advantages to large scopes and there are advantages to smaller scopes. If you are like me and have the larger apertures well represented (two 12.5", 16", 25"), then the purpose of a small scope is to do the things that a small scope does best.
It's true that a C-5 is more portable than a 4 or 5 inch refractor but the difference is not great. What is important are those things a smaller scope does best, super wide, well corrected field of view, you are not going to see the entire Veil or Andromeda in a C-5, the Pleiades are not really going to fit... That is one side of the equation. The other side, viewing the planets, splitting double stars, the efficiency of a refractor and perfection of the view comes into play, there is no central obstruction, fewer optical compromises and a refractor has few thermal stability issues.
If one is most interested in getting the best view for your dollar then I suggest a 130mm F/5 Newtonian fitted with a 2 inch focuser. At the high magnifications it is good performer, splitting double stars to the limit and providing good quality planetary views. In this aspect it will be at least as good as the c-5, at least that was my experience when I owned both. At the other end, the low powers, it does a good job of imitating a refractor, a 3.5 degree TFoV is possible.
Jon
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jgraham
Postmaster
Reged: 12/02/04
Loc: Dayton, Ohio
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Re: Why a refractor over a larger SCT at less cost?
[Re: Jon Isaacs]
#5215572 - 05/10/12 01:47 PM
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Until I bought my AR-6 my SC8 was my favorite general-purpose scope. I still like my SC8 and I wouldn't trade it for anything, but I just enjoy the refractor soooo much. Part of it is how trouble-free it is. Once collimated there's really nothing to adjust (and it hold collimation fine) and it thermally equalibrates so fast I just set it up and observe.
The next two nights look wonderful! I'll have my LXD75 SN6/T2i out for imaging and my LXD75 AR-6 out to enjoy the view. Gonna be fun.
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orion61
Vendor(Clear Edge Optical)
Reged: 10/20/07
Loc: NW Iowa BURRRR
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Re: Why a refractor over a larger SCT at less cost?
[Re: The Mekon]
#5215711 - 05/10/12 02:54 PM
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Aperture does not always rule. I have never seen an 8" SCT that can come close to the views that my 130 AP delivers. And that includes deep sky objects.
For cost scope for scope, a C14 is going to out perform that refractor any day,
I had it proven to me at a star party. The 14 had to use a ND filter to reduce the brightness, to achieve similar mags.
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sg6
sage
Reged: 02/14/10
Loc: Norfolk, UK.
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Re: Why a refractor over a larger SCT at less cost?
[Re: jgraham]
#5215723 - 05/10/12 02:59 PM
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Because a refractor has a soul.
And,
Quote:
because SCTs are inherently evil and refractors are virtuous !
Apos, in particular, have been known to cure gout, hare-lip,
ED, and a host of embarassing skin conditions.
I have found that even a small refractor will give a sharper image then an SCT and although the image may be smaller the detail is more apparent.
To be honest I was somewhat disappointed by the SCT performance as the image (Jupiter) really through the SCT should have far exceeded the small refractor, achro.
Yes I like refractors but if the SCT had been better I would be honest. Maybe the SCT had a problem?
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: Why a refractor over a larger SCT at less cost?
[Re: sg6]
#5215834 - 05/10/12 04:06 PM
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Yes I like refractors but if the SCT had been better I would be honest. Maybe the SCT had a problem?
SCT's take some real time to reach thermal equilibrium, they need to be collimated spot on and of course, to take advantage of a larger aperture, the seeing has to be sufficiently stable.
Jon
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la200o
Pooh-Bah
Reged: 09/09/08
Loc: SE Michigan, USA
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Re: Why a refractor over a larger SCT at less cost?
[Re: Jon Isaacs]
#5216470 - 05/11/12 12:41 AM
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Collimation can be an issue with an SCT; rarely with a refractor.
Bill
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