234 replies to this topic

[MellonLake]

Small refractors are great for quick viewing and for wide field views.  If you have good seeing and/or good transparency, aperture rules for pretty much everything other than the really big DSOs.  Most of us have a small refractor to complement our bigger telescopes for those wide field views.   I set up in on a very good seeing and transparency night June beside 120mm and 130mm triplet apo refractors with my 16" Dob...there was really no comparison... the Dob blew the refractors out of the water... every object we looked at the Dob was significantly better, Jupiter, Saturn, Crescent Nebula, Veil Nebula...... On another night where seeing was poor, the difference was not so great.   

 

Refractors are great grab and go telescopes and great for big DSOs but beyond that aperture rules (except in poor seeing when things equal out).  

 

Rob

[NeroStar]

My refractors are my grab and go scopes, and when I need a light bucket, I'll grab my CPC-1100 (now pier-mounted in my observatory).  When doing AP, aperture is more or less a moot point.  It all depends on what you're shooting or viewing whether one scope or another is optimal for the task.  I like refactors for their slightly wider FOV and low-maintenance qualities.  A horrible road bump once sent my big SCT out of collimation while my refractor was practically screaming to get out into the field when I got to the observing site.

 

The 'This or That' conversation regarding reflectors and refractors really has no answer.  They're complimentary tools.  It's like arguing whether a hammer is better than a drill. They can both help you build a house.   

[bigeastro]

The OP already owns a C9.25. He is thinking of another scope to compliment his C9.25.   If I had that scope, and wanted to piggyback something on it, it would be a small rich field APO refractor.  Something on the order of 80 to 100mm aperture.  Even if it was just for visual, I would spend the money for a true APO instead of an ED.   I would look closely at a CFF92  (correction CFF92 currently not available) or a Stellarvue SVX90T which are readily available to a certain extent.  I think that probably somewhat matches the price point of a C925 but is a little higher than that price point all things considered, but the quality is excellent.  Knowing what I know now, I would probably start to collect the higher quality scopes in the small aperture first and then move on and trade up as the years go by.

Edited by bigeastro, 27 January 2023 - 02:38 PM.

[Polyphemos]

It kinda goes like this

https://m.youtube.co...h?v=xaK4r0pQaJ0

And yet I am no wiser.   I’m looking for a scope more like this..

 

https://www.youtube....h?v=TRjH_gJbUqQ
 

[JoshUrban]

If the house was burning down, I'd save my 12.5" f/5 dob.  Since it's not, I quite enjoy a refractor view, too.  NeroStar makes a great point about it being like a drill vs. hammer.  It's a different experience, and the sky has many wonderful ways to look at it.  

 

  Folks do get sidetracked with quality shootouts..."My apo will knock ___ reflector out"  or "My five hundred dollar dob can see further than your five thousand dollar Tak."  It's optical drag racing (and I definitely partake.)  Now, it is fun to pit a Porsche (high end apo) vs. a homebuild franken-Newt with a handbuilt 383..err...mirror.  Anytime folks do that, I try to be around.  And, when there's money and effort involved in anything, there's gonna be bias.  

 

  The thing I like to remember with scopes is "best" is subjective.  It's not always getting down the quarter first, or seeing an IC galaxy.  What's a nice way to marvel at some ancient starlight?  I don't think I've met a telescope I didn't like.  

 

  Personally, I'm digging my new f/11 102mm ED refractor.  The contrasty views, and classic observing experience count for a lot.   "Pedestrian" M35 knocked my socks off the other night.   The cost of properly mounting it have me grumbling in my "dob camp" voice.  

 

  I think you'd dig a small refractor.  It's a nice, wide open view of the universe.  And, if you'd like us to spend all of your money, a fast dob would be a nice compliment to your SCT.  Personally, I wouldn't mount it on your big scope.  The freedom of a grab 'n go would be negated.  

[Echolight]

And yet I am no wiser.   I’m looking for a scope more like this..

 

https://www.youtube....h?v=TRjH_gJbUqQ
 

Thar was just putting it together. 
 

It ended up like THIS

https://m.youtube.co...h?v=p-HI3kd5jPc

[Sketcher]

For me (a strictly visual observer), I think it's mostly a matter of ease of use (for the ways in which I prefer to use a telescope) combined with ease of maintaining and caring for the instruments.  I've been able to keep my refractor optics in pristine condition.  Each and every time I take out my oldest refractor its optics are every bit as clean and pristine as they were upon first opening the straight-from-the-manufacturer box some 28 years ago.  And as many are aware, cleaner optics translate to less scattered light and higher contrast views.

 

It doesn't bother me to stick with smaller aperture, refractive telescopes.  They're fully capable of showing me more than I've ever desired to see.

 

Mostly, my refractors are achromats; but I also have refractors that occupy each end of the quality scale -- a singlet refractor at one end and an apochromat at the other end.  I enjoy each refractor type for its own unique set of strengths and weaknesses.  I enjoy seeing celestial bodies much the same as some of history's visual refractor observers saw the same objects (It helps that I enjoy similar sky conditions  )

 

At the smallest of apertures, the refractor is king.  At typical amateur refractor apertures, aperture for aperture, the refractor is the most efficient design for raw light-grasp.  But, of course, image sharpness and contrast will vary a bit depending on the specific refractor.  At the high end (an apochromat of the highest quality), aperture for aperture, the refractor will provide sharper and higher contrast views than any other telescope type.

 

When one considers what a really small refractor is capable of, one needn't go very large in order to get some truly spectacular views:

 

For example, a 1-inch aperture used for lunar observation:

 

 

and, under a seriously dark sky, a 1-inch aperture for deep sky observation:

 

 

Of course, lunar details (in a 1-inch refractor) are much smaller than those shown in the first sketch; and deep sky views are much fainter than what is shown in that second sketch.  But, with experience, one learns to pick out fine detail even when the view in the eyepiece is quite small; and one also learns to pick out faint details in deep sky objects.  It's worth noting that as far as the details that appear in the above sketches go, those sketches are accurate and true to what was seen visually.

 

Imagine how much more could be seen with double the aperture, for example, with the below 2-inch refractor:

 

 

Yet, I have the option of setting up even larger 3.14-inch, 5.1-inch, and 6-inch refractors -- up to six times the aperture that was used for the above observations/sketches.

 

So really, refractors can provide me with all the aperture that I could ever desire.  But I guess I needed to acquire and use 10-inch and a 12-inch Newtonians before I came to that realization.  Anyway, those larger telescopes haven't been used in several years.  Their advantages (and yes, they do have advantages) are outweighed (for me) by their disadvantages.

 

For me, I think it mostly boils down to ease and suitability of use and ease of care/maintenance; but it doesn't hurt that refractors can also perfom  .

[mikemarotta]

1. Portability. One highly recommended beginner telescope is a 6-inch Dobsonian. The telescope weighs 25 lbs. The base weighs 35 lbs. On the other hand, my "grab-n-go" 4-inch refractor and its mount and tripod weigh 25 lbs combined. If you are a small person or you have mobility problems, the portability of a smaller telescope is important. The best telescope is the one that gets used.

 

2. Convenience. My 4-inch "grab-n-go" refractor was in for repairs and I enjoyed using a 5-inch Newtonian (Astronomers Withouth Borders). However, several nights, I wanted to go out, but had not planned on doing so and the telescope had not been collimated. I knew from experience that collimation needed to be set (or at least checked) each time. So, those nights I did not have the use of the nominally "better" telescope with more aperture. Also, just to say, at a local star party I helped one of our stalwarts collimate his 8-inch Dobsonian twice. It took two of us: one to view, one to turn the knobs. One person can do it alone: back and forth... back and forth... back and forth...

 

3. Choice of Aberrations.  An achromatic refractor does have chromatic aberration. An apochromatic has much less (theoretically none, but theoretically also still a tiny bit). A Newtonian reflector has wires ("spider vanes") that create diffraction interference. Some people like the look of that so much that they photoshop spikes into all of their stars. 

 

4. Actual aperture is the actual aperture. With a Newtonian, you have the central obstruction is which is usually given as 25%. (Some makes and models have more.) So, an 8-inch reflector is really a 6-inch aperture. So, the highly recommended 6-inch entry-level Newtonian is really a 4.5 inch entry-level telescope, just heavier to carry in two trips.

 

Those all being my reasons, the fact is that my first adult telescope was a Newtonian, a 130mm Celestron on an equatorial mount and I used it happily for five years and learned a lot about the sky. The best telescope is the one that gets used.

 

I am strictly a visual observer. (I have taken some snapshots with my cellphone.) Observing is my hands-on engagement in the hobby. My primary interest is in writing and I also volunteer as an editor. As much as I support other people's being "Citizen Scientists" I know that I am not. I do not track variable stars or look for comets. I am just a stargazer, as probably 90% of us here are. We are less engaged with celestial objects than birdwatrchers are with their feathered friends. Birdwatchers will put out feeding stations and hang housing from the trees and be mindful about keeping the cat indoors. We do nothing to help the stars. Even photographers contribute very little to science. (I know: there is a counter-argument from a Sky & Telescope article. but the fact remains that most astrophotography is just another kind of stargazing.)

 

Clear Skies,

Mike M.

Edited by mikemarotta, 27 January 2023 - 06:52 PM.

[vtornado]

I have refractors for quick peaks.   

Cooling is substantially less time than a large mirrored scope.

Also I don't have to check collimation.

Refractors scale down very well, they don't scale up very well.

An 80mm or 100mm reflector suffers from large central obstruction.

I use my small refractor for terrestrial.  There is no secondary shadow.

Once refractors get over 4 inches cost and mounting requirement increase quickly.

 

My 100 Achro and 80 ED are my most used scopes, because of their ease of use.

[Waynosworld]

The Refractor and Larger Dobs have different uses, I take both when I can go to a dark site, it is awesome to observe complete large objects like the Veil Nebula with the Refractor, I cannot even fit half of it in my 16" dob with a 35mm Panoptic eyepiece, it looks better in the Refractor in my opinion, what I mean is Mt St Helens looks better as a complete object than looking at just the dome inside the crater although that is cool too.

[Protheus]

Refractors are nice telescopes.  You get an objective with the full aperture clear, and the better ones have very few optical problems, often less obvious compared to, say, Newtonian coma.  They're really only convenient in small apertures, and they're more expensive relative to the diameter, so this limits the popularity of the large ones a bit.  They make a very nice, if slightly expensive, small scope, though.

 

Chris

[quercuslobata]

1. Portability. One highly recommended beginner telescope is a 6-inch Dobsonian. The telescope weighs 25 lbs. The base weighs 35 lbs. On the other hand, my "grab-n-go" 4-inch refractor and its mount and tripod weigh 25 lbs combined. If you are a small person or you have mobility problems, the portability of a smaller telescope is important. The best telescope is the one that gets used.

 

2. Convenience. My 4-inch "grab-n-go" refractor was in for repairs and I enjoyed using a 5-inch Newtonian (Astronomers Withouth Borders). However, several nights, I wanted to go out, but had not planned on doing so and the telescope had not been collimated. I knew from experience that collimation needed to be set (or at least checked) each time. So, those nights I did not have the use of the nominally "better" telescope with more aperture. Also, just to say, at a local star party I helped one of our stalwarts collimate his 8-inch Dobsonian twice. It took two of us: one to view, one to turn the knobs. One person can do it alone: back and forth... back and forth... back and forth...

 

3. Choice of Aberrations.  An achromatic refractor does have chromatic aberration. An apochromatic has much less (theoretically none, but theoretically also still a tiny bit). A Newtonian reflector has wires ("spider vanes") that create diffraction interference. Some people like the look of that so much that they photoshop spikes into all of their stars. 

 

4. Actual aperture is the actual aperture. With a Newtonian, you have the central obstruction is which is usually given as 25%. (Some makes and models have more.) So, an 8-inch reflector is really a 6-inch aperture. So, the highly recommended 6-inch entry-level Newtonian is really a 4.5 inch entry-level telescope, just heavier to carry in two trips.

 

Those all being my reasons, the fact is that my first adult telescope was a Newtonian, a 130mm Celestron on an equatorial mount and I used it happily for five years and learned a lot about the sky. The best telescope is the one that gets used.

 

I am strictly a visual observer. (I have taken some snapshots with my cellphone.) Observing is my hands-on engagement in the hobby. My primary interest is in writing and I also volunteer as an editor. As much as I support other people's being "Citizen Scientists" I know that I am not. I do not track variable stars or look for comets. I am just a stargazer, as probably 90% of us here are. We are less engaged with celestial objects than birdwatrchers are with their feathered friends. Birdwatchers will put out feeding stations and hang housing from the trees and be mindful about keeping the cat indoors. We do nothing to help the stars. Even photographers contribute very little to science. (I know: there is a counter-argument from a Sky & Telescope article. but the fact remains that most astrophotography is just another kind of stargazing.)

 

Clear Skies,

Mike M.

I agree with a lot of this and what others have said. My 72mm refractor is perfect for winter viewing especially. You get a rare partly cloudy night so you know you have to get out there, but it is cold enough that it is one of those Mars, Pleiades, Orion Nebula, and done nights. I’m not dragging the 8” dob out for that.

 

One thing about the relative aperture though, isn’t it the obstruction by area that is important? So the reduction in effective aperture is not quite so severe as that? I only say this because as a newbie it was really confusing to me.

Edited by quercuslobata, 28 January 2023 - 09:12 AM.

[dnayakan]

 

One thing about the relative aperture though, isn’t it the obstruction by area that is important? So the reduction in effective aperture is not quite so severe as that? I only say this because as a newbie it was really confusing to me.

You can do the math. Area of primary mirror - area of central obstruction. Assuming a 30% central obstruction, actual surface area for light gathering is pi * r ^2 - pi * 0.3 r ^2 = pi * 0.91 * r ^2. So the loss in light gathering due to the central obstruction is along the lines of 10%. However, the central obstruction also increases diffraction and lowers contrast and so people add a bit of ‘subjective, qualitative’ penalty.

 

Cheers, DJ

[gnowellsct]

Personally, I wouldn't mount it on your big scope. The freedom of a grab 'n go would be negated.

That's a misconception. The refractor can go on its own dovetail and be mounted on the larger scope. When you're done you just take it off. It can then be independently mounted on its own mount.

Even if you're not mounting the secondary scope with a dovetail. About the only other option is to have rings permanently mounted on the primary scope. In that case you can get a second set of rings on a dovetail and pull the secondary scope off the primary scope by opening the rings, which is not hard, putting it into the second set of rings with their dovetail and again you're ready to go.

Unless one has an observatory, it would be a bad idea to leave the secondary scope on the primary scope in any case. So you always have the grab and go potential. You would need a Twilight or similar mount for such applications.

[gnowellsct]

(disclaimer: I am considering buying a refractor to supplement my Celestron 9.25 and to possibly double mount it).

I use 92 mm double mounted on my C8 and also on my c 14. I also use refractors independently of the scts. But I would have to say I get the most enjoyment out of the combination rig.

Greg N

[rgk901]

I agree, my 50mm rides the bigger scopes well and also my light tripod.

 

I use rings with a finder foot and switch between the bigger scopes and my tripod depending what I'm doing and how much stuff I want to have with me.

[HouseBuilder328]

I use 92 mm double mounted on my C8 and also on my c 14. I also use refractors independently of the scts. But I would have to say I get the most enjoyment out of the combination rig.

Greg N

 

Yep, seems like a lot of people who have double mounted telescopes that complement each other have the most fun.   My Evolution mount most likely can’t handle both the C9.25 and a refractor (unless it’s a 60-72mm) but even then I think it will be shaky with the motors.  

 

Probably will get the Sky-Watcher AZ-EQ6 Pro but that’s another $2500-2600.   I need a GoTo mount and would prefer AZ-Alt. 

[Lizardman]

For me two simple reasons ( assuming a 100mm +_mm refractor) ; portability and not having to mess with collimating them.

[tony_spina]

Because refractors are better than reflectors.  There I said it!  

[Lizardman]

Because refractors are better than reflectors. There I said it!

Exactly that’s all the reply required to answer the question

Edited by Lizardman, 28 January 2023 - 01:36 PM.

[jgraham]

That's an interesting question. My guess is that for starters a lot of us started with a small refractor. They can be very affordable and the work quite well. As we gain experience we can appreciate how well they can work with a little tweaking. After 60 years in the hobby I have used, built, and owned quite a few scopes and each one has its place. Broadly, Newtonians often offer the largest aperture for the cost, compound telescopes (CCs, SCTs, MCTs, etc.) pack a lot of scope into a small package, refractors are somewhat size limited, but are _extremely_ easy to use, and usually produce a fine image. As we gain experience as observers we often learn to see more with less and that can often offset the smaller aperture of a typical refractor. Also, refractors tend to perform above their size class as they usually have lower sources of light loss as compared to a reflector (no secondary, and no light loss per reflection) and they can produce an exceptionally sharp image (no secondary to move light from the Airy disk out into the diffraction rings). If I want to go deep I tend to get out one of my larger scopes, like a 16" Dob or a 12" SCT, but for a relaxing night out under the stars I tend to get out one of my refractors. My absolute favorite is my wonderful 1960s vintage 4" f/15 Unitron. The view through this scope has set the high bar for sharpness that only my largest scopes can surpass by brute force of aperture.

 

I have a set of rings that I can use to put my Unitron on a modern GoTo mount...

 

 

...but for outreach and an evening of star-hopping I like to use it on its original mount...

 

 

What a fun hobby!

 

 

[Dave Mitsky]

I own a number of small refractors, a number of larger Newtonians on equatorial and Dobsonian mounts, and one small SCT.  

 

I love using my 101mm f/5.4 Tele Vue Petzval refractor.  It can produce a very wide TFOV of 4.4 degrees and yet is excellent at high powers as well.

 

 

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[Jethro7]

Hello,

I will admit unbashfully right up front that I am a refractor junkie. I find this Genre of telescopes elegant and so easy to set up. I own quite a few refractors now, from 60mm to 152mm and can easily find the justification to purchase another. Through a well designed refractor, the views are very sharp and crystal clear with a beautiful contrast. Some nights I only have a couple of of hours to view, the Dob takes half of that time up just to reach temperature. The cool down time for my Refractors, about 10 to 15 minutes or about the time it takes to set everything up. Many nights my sky conditions simply will not favor the large aperture of a Dob anyway and my refractors are still good to go. For me the biggest advancement in technology for viewing with my refractors, greatly enhancing a refractors capabilities, has been the  purchase of a light intensifier, that allows me to hunt down DSO's of all maner from my Bortle 7-8 Backyard, DSO's that I could never have imagined possible with a refractor, even small aperture refractors. All of this just adds to my love of refractor Genre.

 

HAPPY SKIES AND KEEP LOOKING UP 

 

 

 

Light itensifier, the game changer for refractors

 

 

 

 

Edited by Jethro7, 29 January 2023 - 06:28 PM.

[BlueTrane2028]

Refractors...

I have had a bunch of f/5 plain achromats, ST80, ST102 and ST120.

The 80 didn't pull enough light to interest me much, the 102 was a nice casual scope when on a light alt-az mount and the 120 is a fun one to pursue faint fuzzies.

NONE of them are capable of anything close to higher magnifications and you get tons of false color around bright stars and planets.

I've arrived at the AT102ED as my refractor option that's likely to stay around.

It works nicely on a CG4 manual EQ mount.  It has about the same focal length as the ST120 and a great 2" focuser, so a decent wide field eyepiece around 30mm is a spacewalk.  What it can do that the others I've had cannot is... pursue planets and high powers too.  I got a pretty nice Jupiter view with that telescope and a 3.5mm Orion Stratus eyepiece.

If you're able to wrap your mind around an equatorial mount, I really have a hard time coming up with reasons why a beginner shouldn't have the AT102ED/CG4 combo in their potential scope list... with the noted exception that an 8" Dob pulls in 4x the light and goes a lot deeper... and is cheaper too.  The combo is currently at $950, plus you need to provide your own finder, diagonal and eyepieces.

I don't like to use my Dob for solar, but a Herschel wedge makes the AT102ED very nice indeed for white light solar.   It gets the most use in that way at present.

https://www.astronom...ractor-ota.html

https://www.astronom...rial-mount.html

[BlueTrane2028]

I use 92 mm double mounted on my C8 and also on my c 14. I also use refractors independently of the scts. But I would have to say I get the most enjoyment out of the combination rig.

Greg N

If I strapped my ST80 onto my C8, it might save the ST80 for me...  I might have to try it.  I have little interest in the scope by itself, but it wouln't be too particularly taxing to add to my mount.