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Refractor advice for DSO viewing

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#1 Wesker

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Posted 21 January 2021 - 01:02 AM

So here’s the situation. Have a Z8 dob and some pretty respectable eyepieces. But the son (9) is now super into space and wants to participate. Makes me super happy, but not sure the dob is the choice. With work and young kids, the dob unfortunately becomes more decoration and less instrument of use. The simple fact is, it won’t fit in the car with the kids on a drive to dark skies. And it’s a pain to lug out even to the balcony at the drop of a hat.

 

I think my son and I would get a lot more use and therefore enjoyment out of a decent refractor. It’d be nice to be able to use it for planets and the moon, but the dob always works for that at home. I’m wondering what a good refractor would be for trips to dark sky to see DSO. And by that I really mean primarily the Messier list.

 

Im hoping not to break the bank and would like to keep it under 500. And I’m also hoping my eyepieces would work with it. Refractors are rather foreign to me although I’ve been researching and reading reviews. Do they make them that will accept 2” eyepieces?

 

The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5.


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#2 Wouter1981

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Posted 21 January 2021 - 01:30 AM

In your case, I would directly look at a 100-120mm achromat shorttube. The skywatcher 100-120 startravel comes with a 2 inch focuser and the mount included is rather lightweight.

 

https://www.teleskop...or-120-600.html

 

It's not perfect. The focuser is rather crude, the mount isn't that super, but it all works and for the money, it's really a great lightweight package.


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#3 Jay_Bird

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Posted 21 January 2021 - 01:31 AM

Astronomics sells the Astro Tech ED 80mm for $400. The same price will get you a 102mm achromat that will show some false color but may work fine for your purposes

Either will work for deep sky, moon and planets with your current eyepieces. About $100 should be close to a 2-inch diagonal. You can get by with a red dot finder.

Since you mentioned driving to dark skies this will do great on many clusters and more. The wide field will let you see veil, helix, double cluster etc., and even nice views of brighter galaxies m31 or ngc253 - all possible using a small scope under dark skies which are like adding inches of aperture. I got a lot of camping use out of 80 and 102mm achromats.
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#4 Bob4BVM

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Posted 21 January 2021 - 02:41 AM

There is a Celestron c6r OTA 6" in the classifieds right now for $300, that would be my choice for a 'frac for DSOs

You want the kids to see them as bight as possible , not the dim smudges presented in small apertures.

For DSOs apertures rules, just like in reflectors. Get as much of it as you can, keep their interest going !

CS

Bob



#5 sg6

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Posted 21 January 2021 - 03:51 AM

The idea of an 80ED would to me seem the best. Jay-Bird's suggestion.

I have a 102/600, nice size, "portable" but the CA holds it back. And owning to that if you went for an achro then it would I suggest have to be longer then f/6 means.

 

ES/Bresser do a 102 in either 1000mm or 1200mm but by then they are getting long and not portable.

 

An 80 will show a lot of DSO's - pick the easy ones, make life simple.

One slight hiccup is - The mount?

Guessing you don't have one.

Manual means something along the lines of the ES Nano, or Twilight. The Vixen Portamount (??) seems nice but costs more. Not sure of Skywatcher offerings, or rebrands.

 

80ED would fit nicely on the Skywatcher Az GTi and give you (son) a goto. More $$ however.

The 80ED would also go well with a solar filter or Herschel Wedge for solar - do we still have a sun?

 

Lesser cost would be the ES/Bresser AR or Firstlight 80/640 achro on their Nano mount. Was around $220. At f/8 CA should be reasonable. And cost is less, well until son wants something better.

 

Oh yes, the 80ED would also cover beginner imaging. Quite a versatile little scope overall.

 

Final alternative: Bigger car.


Edited by sg6, 21 January 2021 - 03:52 AM.

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#6 Stefano Delmonte

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Posted 21 January 2021 - 05:12 AM

I'm with Wouter1981 , a 120/600 achro will be an easy telescope to use for low med power for open clusters large  nebulas and the extra diameter will help, maybe an 9 years old kid will not be able to appreciate the ED lenses but will appreciaate the extra diameter.

 

By the way, are you sure a kid will not be able to use a dobson, the master in ergonomics?!?

 

Ste


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#7 PETER DREW

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Posted 21 January 2021 - 05:29 AM

I'm with Wouter and Stephano. A 120mm short focus refractor would be ideal for most DSO's, CA is a non event for low power wide angle viewing.  A 120 would just about be ok on a manageable mount.  An 80mm ED is a fine telescope but perhaps best left until astrophotography is a main consideration.  


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#8 sportsmed

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Posted 22 January 2021 - 04:12 AM

Yea I'm with some of the other suggestions, if you are mainly going to use the scope for DSO then aperture is key. Also you would still want fairly wide field views for some DSO. So for the price range I would go with a 120mm/ 600 focal length scope like the Orion ST120 or a Sky Watcher etc. What mount are you putting it on? Also the suggestion on a 80mm ED could be an option for better optics if you want to look at planets or other bright objects but it will leave alot of DSO fainter compared to the 120mm. I do have a ST80 though and you can see quite a bit for its size and I love the wide field views.


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#9 bobhen

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Posted 22 January 2021 - 08:32 AM

If you want to view deep sky objects, the StarTravel 102 F5 or the Orion 120 F5 are solid choices. I have owned both and still have a 102mm F5 that I have owned for 16 years. You can of course still get some casual views of the moon and planets but the main forte of these scopes is deep sky observing.

 

A simple alt/az mount is all that is needed. Just get the one that fits your budget and the scope you pick. The Orion VersaGo II ($179) or the Vixen Porta II ($299) would be candidates.

 

HERE is a nice review of the 102 F5 refractor

HERE is a video review of the Orion 120 F5 refractor

 

Bob


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#10 Bob4BVM

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Posted 23 January 2021 - 03:18 PM

Reading all this, i must be missing something. The title says 'for DSO viewing' , yet all these suggestions for 80-100mm scopes !

You already have an 8" Dob whose DSO views would squash views in these smaller apertures. 

 

"not sure the dob is the choice"  ???

I do a fair amount of school outreach and kids have no problem using a small Dob in the 6-8-10" range. Easy to move and the EP height is perfect for them. And they are blown away by what they see in the EP - that is the key point, it is what they remember, its what gets them to go out and look up at night instead of playing video games.

  

I have a 6" frac i love to use for widefield, that is its forte'. The wide, crystal clear views are awesome.

But when i go out for some serious DSO hunting i take the biggest gun i have.  

 

CS

Bob


Edited by Bob4BVM, 23 January 2021 - 03:21 PM.

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#11 junomike

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Posted 23 January 2021 - 06:13 PM

Reading all this, i must be missing something. The title says 'for DSO viewing' , yet all these suggestions for 80-100mm scopes !

You already have an 8" Dob whose DSO views would squash views in these smaller apertures. 

 

"not sure the dob is the choice"  ???

I do a fair amount of school outreach and kids have no problem using a small Dob in the 6-8-10" range. Easy to move and the EP height is perfect for them. And they are blown away by what they see in the EP - that is the key point, it is what they remember, its what gets them to go out and look up at night instead of playing video games.

  

I have a 6" frac i love to use for widefield, that is its forte'. The wide, crystal clear views are awesome.

But when i go out for some serious DSO hunting i take the biggest gun i have.  

 

CS

Bob

 

So here’s the situation. Have a Z8 dob and some pretty respectable eyepieces. But the son (9) is now super into space and wants to participate. Makes me super happy, but not sure the dob is the choice. With work and young kids, the dob unfortunately becomes more decoration and less instrument of use. The simple fact is, it won’t fit in the car with the kids on a drive to dark skies. And it’s a pain to lug out even to the balcony at the drop of a hat.

 

I think my son and I would get a lot more use and therefore enjoyment out of a decent refractor. It’d be nice to be able to use it for planets and the moon, but the dob always works for that at home. I’m wondering what a good refractor would be for trips to dark sky to see DSO. And by that I really mean primarily the Messier list.

 

Im hoping not to break the bank and would like to keep it under 500. And I’m also hoping my eyepieces would work with it. Refractors are rather foreign to me although I’ve been researching and reading reviews. Do they make them that will accept 2” eyepieces?

 

The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5.

 

 


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#12 Echolight

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Posted 23 January 2021 - 08:29 PM

I've been thinking about an ST120 as a biggest little scope for quite a while. One that could be packed in a tight space and go on a small mount for grab and go. One with more reach and light gathering than an ED80.

 

Sometimes I think maybe a C6 SCT instead. But a max true field of view is only about 1.7 degrees.



#13 peta62

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Posted 23 January 2021 - 08:59 PM

I agree with all those 120 f/5 ideas. Just your eyepieces will definitely be too short. If you are on a tight budget you can check Surplus shed for eyepieces like  https://www.surpluss...tem/L14723.html and https://www.surplusshed.com/pages/item/L2008A.html .


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#14 Jon Isaacs

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Posted 23 January 2021 - 09:26 PM

I agree with all those 120 f/5 ideas. Just your eyepieces will definitely be too short. If you are on a tight budget you can check Surplus shed for eyepieces like  https://www.surpluss...tem/L14723.html and https://www.surplusshed.com/pages/item/L2008A.html .

 

Wesker's eyepieces:

 

"The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5."

 

The ES 30mm is very similar to the 31mm Nagler.  In the 120mm F/6 it provides a 4.0 degree field at 20x with a 6mm exit pupil..  It doesn't get any better than that.  And the APM 20mm 100 degree a 3.3 degree field at 30x with a 4mm exit pupil.

 

I think Wesker's set for eyepieces.

 

Jon


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#15 SteveG

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Posted 23 January 2021 - 09:29 PM

A budget 100-120 mm achro on an Alt/Az mount is what you need, as most here have noted. Don't skimp on the mount. The Porta II is very good, even better on an improved tripod.


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#16 peta62

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Posted 24 January 2021 - 03:53 AM

Wesker's eyepieces:

 

"The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5."

 

The ES 30mm is very similar to the 31mm Nagler.  In the 120mm F/6 it provides a 4.0 degree field at 20x with a 6mm exit pupil..  It doesn't get any better than that.  And the APM 20mm 100 degree a 3.3 degree field at 30x with a 4mm exit pupil.

 

I think Wesker's set for eyepieces.

 

Jon

Oh shoooot, of course you are right, I overlooked the 30  and 20 mm. I should have some self control not to write when I am dead tired. Thank you for correction.


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#17 russell23

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Posted 24 January 2021 - 07:37 AM

So here’s the situation. Have a Z8 dob and some pretty respectable eyepieces. But the son (9) is now super into space and wants to participate. Makes me super happy, but not sure the dob is the choice. With work and young kids, the dob unfortunately becomes more decoration and less instrument of use. The simple fact is, it won’t fit in the car with the kids on a drive to dark skies. And it’s a pain to lug out even to the balcony at the drop of a hat.

 

I think my son and I would get a lot more use and therefore enjoyment out of a decent refractor. It’d be nice to be able to use it for planets and the moon, but the dob always works for that at home. I’m wondering what a good refractor would be for trips to dark sky to see DSO. And by that I really mean primarily the Messier list.

 

Im hoping not to break the bank and would like to keep it under 500. And I’m also hoping my eyepieces would work with it. Refractors are rather foreign to me although I’ve been researching and reading reviews. Do they make them that will accept 2” eyepieces?

 

The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5.

You have a great eyepiece line-up that will work well with a refractor.   Do you already have a mount for whatever refractor you select?  If not then you need to factor that into the total cost.  

 

If you want to use it for planets than the ST120 is not a great option.  The AT102ED or the AT80ED would be better options for planetary.  The 80mm would ride nicely on a Vixen Porta II mount.  

 

But you can see that in terms of budget, to get started with a refractor you’re going to need to spend at least as much as your dob if you want to include the planets.


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#18 LDW47

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Posted 24 January 2021 - 09:53 AM

Reading all this, i must be missing something. The title says 'for DSO viewing' , yet all these suggestions for 80-100mm scopes !

You already have an 8" Dob whose DSO views would squash views in these smaller apertures. 

 

"not sure the dob is the choice"  ???

I do a fair amount of school outreach and kids have no problem using a small Dob in the 6-8-10" range. Easy to move and the EP height is perfect for them. And they are blown away by what they see in the EP - that is the key point, it is what they remember, its what gets them to go out and look up at night instead of playing video games.

  

I have a 6" frac i love to use for widefield, that is its forte'. The wide, crystal clear views are awesome.

But when i go out for some serious DSO hunting i take the biggest gun i have.  

 

CS

Bob

Come on now look at the age of the operator ! 9 years old, give him time !


Edited by LDW47, 24 January 2021 - 09:54 AM.

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#19 LDW47

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Posted 24 January 2021 - 09:59 AM

120mm ST all the way, its impressive, it puts out some great low power, up to 70x, wide field views and its easily workable for a 9 yr. old with a bit of help at times. The only upgrade might be to say a Twilite I mount, they usually come with an AZ3, a no go ! They are a very, very capable scope for a young up and comer with a dad beside him, until he wants to do it all by himself, lol !


Edited by LDW47, 24 January 2021 - 10:09 AM.


#20 LDW47

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Posted 24 January 2021 - 10:01 AM

A budget 100-120 mm achro on an Alt/Az mount is what you need, as most here have noted. Don't skimp on the mount. The Porta II is very good, even better on an improved tripod.

The tripod on the Porta II is good enough, stable enough for now, for a 9 yr old especially if the legs can be retracted some due to the users young height !



#21 russell23

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Posted 24 January 2021 - 10:42 AM

120mm ST all the way, its impressive, it puts out some great low power, up to 70x, wide field views and its easily workable for a 9 yr. old with a bit of help at times. The only upgrade might be to say a Twilite I mount, they usually come with an AZ3, a no go ! They are a very, very capable scope for a young up and comer with a dad beside him, until he wants to do it all by himself, lol !

That is a good point about the age of the young person.  I’m still a bit iffy on the ST120 because of the severe CA when the easiest targets for the young person would be the Moon and planets.  It does provide more reach for deep sky, but OTOH, the light gain over a 102mm is only about 38%.   

 

And I think the stability of the mount is a hugely important factor.   Nothing worse than not being able to enjoy the view your scope provides because of wobbling that makes it hard to focus and other poor performance characteristics of many cheap mounts.  

 

I think the Porta II with an 80mm f/7 AT ED would be the best combination of stability and capability.  And the OP already has an 8” dob so it is not as if the young person would not have access to deeper light grasp.  


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#22 LDW47

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Posted 24 January 2021 - 11:00 AM

That is a good point about the age of the young person.  I’m still a bit iffy on the ST120 because of the severe CA when the easiest targets for the young person would be the Moon and planets.  It does provide more reach for deep sky, but OTOH, the light gain over a 102mm is only about 38%.   

 

And I think the stability of the mount is a hugely important factor.   Nothing worse than not being able to enjoy the view your scope provides because of wobbling that makes it hard to focus and other poor performance characteristics of many cheap mounts.  

 

I think the Porta II with an 80mm f/7 AT ED would be the best combination of stability and capability.  And the OP already has an 8” dob so it is not as if the young person would not have access to deeper light grasp.  

Do you think a bit of CA, its only a bit from my experience with 80, 102, 120mm achros, means anything to to a young observer at 9 yrs. old ? They will contend with things like that as / if they progress in this great astronomy hobby, if I was that age, again, the looks of a refractor of those 120mm dimensions would be my dream scope especially after I put it through my young paces ! Think like a young, learning astronomer not someone quite a bit older, that time will come. And for dad the price is right, he may even give it a go himself if the young lad will let him, lol ?



#23 LDW47

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Posted 24 January 2021 - 11:03 AM

Also, if you haven’t already, get him a copy of NightWatch, a young persons bible on learning all aspects of astronomy ! 



#24 Wildetelescope

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Posted 24 January 2021 - 11:17 AM

I spend a lot of time with my son using a 60 mm Sears a Achromat that I picked up for 50 dollars. It’s optics are excellent. We have a ball with it on a twighlight 1. The 120mm synta achromats are nice as well. I have an F8 version that does dso’s well and gives actually really nice views of the moon. It is longer, so a bit more demanding of the mount, but really quite nice. And you can pick them
Up used quite cheap. Something to consider.

Good luck!
Jmd

So here’s the situation. Have a Z8 dob and some pretty respectable eyepieces. But the son (9) is now super into space and wants to participate. Makes me super happy, but not sure the dob is the choice. With work and young kids, the dob unfortunately becomes more decoration and less instrument of use. The simple fact is, it won’t fit in the car with the kids on a drive to dark skies. And it’s a pain to lug out even to the balcony at the drop of a hat.

I think my son and I would get a lot more use and therefore enjoyment out of a decent refractor. It’d be nice to be able to use it for planets and the moon, but the dob always works for that at home. I’m wondering what a good refractor would be for trips to dark sky to see DSO. And by that I really mean primarily the Messier list.

Im hoping not to break the bank and would like to keep it under 500. And I’m also hoping my eyepieces would work with it. Refractors are rather foreign to me although I’ve been researching and reading reviews. Do they make them that will accept 2” eyepieces?

The eyepieces I have are the ES30, APM 20 100deg, Morpheus 9 and 6.5, and Meade 5000 5.5.


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#25 russell23

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Posted 24 January 2021 - 11:26 AM

Do you think a bit of CA, its only a bit from my experience with 80, 102, 120mm achros, means anything to to a young observer at 9 yrs. old ? They will contend with things like that as / if they progress in this great astronomy hobby, if I was that age, again, the looks of a refractor of those 120mm dimensions would be my dream scope especially after I put it through my young paces ! Think like a young, learning astronomer not someone quite a bit older, that time will come. And for dad the price is right, he may even give it a go himself if the young lad will let him, lol ?

Yes because planets and the Moon are part of the equation.  There is a huge difference between a 120mm  f/5 and a 120mm f/8.3 achromat where CA is concerned.  If the 120mm f/8.3 achromat was on the table I would give a different answer.    And an 80mm f/5 ST80 is way better than a 120mm f/5 for CA.  The difference in capability between a ST120 and a 102mm f/7 AT doublet is huge with the 102mm f/7 ED as the clearly better choice.  The significant reduction in CA more than compensates for the minimal loss of light gathering.  I would choose the 80mm f/7 over the ST120 as well.  

 

I know because I’ve had every one of these scopes mentioned in this post.  Well I had the SV Access version of the 80mm f/7 which had the FPL-53 glass rather than the FK-61, but based upon the AT102ED f/7 with FK-61 I can extrapolate just fine to the 80mm version.

 

And the mount is not to be ignored.  A mount that is not up to the challenge of the scope really ruins the experience.   Frankly, I don’t know when the idea that a 3”-4” scope is insufficient as a starter scope came about.   Maybe a few more people need to read Leslie Peltier’s “Starlight Nights”.  

 

Unlike the ST120, it is not true to say that the following scopes are limited to 70x magnification:

 

80mm f/11.4 achromat

80mm f/7 ED doublet

90mm f/10.1 achromat

102mm f/7 ED doublet

120mm f/8.3 achromat

 

I’ve owned all of the above and the ST120.  IMO the ST120 is the worst choice of the options I’ve mentioned.


Edited by russell23, 24 January 2021 - 11:27 AM.



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