Grab and go scope

[Aaf146]

Hi guys, I have an 8" dob but am in the process of looking for a nice grab and go scope.

The problem is my budget is quite limited. The obvious choice would be an st80. Then I saw the st102 is not that much more expensive. I've had a look around and seen some others that might fit the bill.

So there's the bresser ar102xs. Nice and small, easy to mount, some lovely wide field views. The problem is its focal ratio is so fast. Has anyone used this and is the chromatic aberration as bad as I imagine. Plus there doesn't seem to be any info on what Ed glass is used, which seems quite suspect.

Then there's the st102 which doesn't have any ed glass but slightly longer focal ratio which might balance it out. Again its small and an easy grab and go.

 

Or would it be better to get something for a similar price with proper ed like a skywatcher 70mm. Obviously it has a smaller objective lens but again will offer nice wide field views and should suffer less from CA due to the better lens.

If anyone can help me with this it'd be greatly appreciated.

Adam

[johninderby]

Had a Bresser 102xs and CA was surprisingly well controlled for a fast achro. The Bresser achros have better optics than the SW ones as well as better build quality and a great CNC R&P focuser but would recommend getting the dual speed knob option.,

Myself I would go for the Bresser 102/600 as it will have less CA although as mentioned the xs isn’t too bad.

Easy to fall o to the just spending a bit more will get ypu a better scope trap. Where does it end? 😁

[Ags]

If I am not mistaken the xs does use a low-dispersion glass element.

[Ags]

8 minutes ago, johninderby said:

Easy to fall o to the just spending a bit more will get ypu a better scope trap. Where does it end? 😁

At the Borg 107 FL.

[StarryEyed]

Buy a cover for the dob and leave it out. If you cant do that put it on wheels. Otherwise the 102/600 which you can also stop it down to 80 or 70 if you use it on the moon which will sharpen it up a lot.

[StarryEyed]

1 minute ago, Ags said:

At the Borg 107 FL.

Thats a really exciting choice. I'll add I had a lot of fun with an ST80. Took it to Ireland and the canary Islands if you have good skies it wont disappoint. 

[Aaf146]

28 minutes ago, Ags said:

If I am not mistaken the xs does use a low-dispersion glass element.

It does but I've heard online from a new people that bresser don't give details of what type of glass they used, hence the hesitancy.

[johninderby]

Bresser says it is ED glass but zero info on what type. I take it as being technically ED but no more than that. However it is good for an achro. 

[Aaf146]

40 minutes ago, johninderby said:

Had a Bresser 102xs and CA was surprisingly well controlled for a fast achro. The Bresser achros have better optics than the SW ones as well as better build quality and a great CNC R&P focuser but would recommend getting the dual speed knob option.,

Myself I would go for the Bresser 102/600 as it will have less CA although as mentioned the xs isn’t too bad.

Easy to fall o to the just spending a bit more will get ypu a better scope trap. Where does it end? 😁

That's always the problem isn't it. Something will be 50 more than a different one, but an even better one will be a little more than that and suddenly you have to sell a couple of children just to pay the mortgage. Thanks for the advice. Did you ever try the xs on the moon or moderate power on the planets.

[Aaf146]

33 minutes ago, StarryEyed said:

Buy a cover for the dob and leave it out. If you cant do that put it on wheels. Otherwise the 102/600 which you can also stop it down to 80 or 70 if you use it on the moon which will sharpen it up a lot.

Neither is practical. My garden isn't flat enough for wheels and I wouldn't want to leave anything outside I cared about losing. Stopping it down might be a good idea. Thanks

[Carbon Brush]

I have just taken delivery of a (new to me) Bresser '102.
I intend it for white light solar, with a continuum filter. Which means CA was not a consideration.

The scope has so far managed seconds between clouds to check for focus with a 2" Herschel wedge.
Not been out in the dark - yet.
So no comments on CA, lens clarity, poor/good blackening in the tube, etc.

I concurr with @johninderby comments on the mechanical build vs Skywatcher ST.
The bundled eyepiece finder and diagonal are the standard kit scope quality. But if you are using it seriously you can upgrade here.
It has the build quality where it matters and the pennies saved on the accessories.

HTH, David.

[johninderby]

I did use the xs on the moon where it gave nice sharp views but with some fringing around the limb and pn Planets it was not too bad so long as ypu didn’t push the mag too much. Bit ot is just an achro although a nice one so be be realistic in your expectations.

Made a great white light solar scope with a Baader solar film filter. 👍🏻

Achros can be exceptional scopes if they are long focal length. My ScopeTech 80 f/15 gives amazing lunar and planetary views. A version is also sold by Takahashi  which tells you how good it is..

https://www.firstlightoptics.com/scopetech-telescopes/scopetech-stl-80a-maxi-80mm-f15-classical-refractor.html

Edited May 21, 2022 by johninderby

[johninderby]

As to the Bresser finder scope replacement problem they now sell a finder base that allows you to fit a Synta type finder.

https://www.telescopehouse.com/Telescope-Accessories/Finder-Scopes/EXPLORE-SCIENTIFIC-Hybrid-Finder-Scope-Base-black.html?mc_cid=bd67484ece&mc_eid=61c9481f7e

[Aaf146]

18 minutes ago, johninderby said:

I did use the xs on the moon where it gave nice sharp views but with some fringing around the limb and pn Planets it was not too bad so long as ypu didn’t push the mag too much. Bit ot is just an achro although a nice one so be be realistic in your expectations.

Made a great white light solar scope with a Baader solar film filter. 👍🏻

Achros can be exceptional scopes if they are long focal length. My ScopeTech 80 f/15 gives amazing lunar and planetary views. A version is also sold by Takahashi  which tells you how good it is..

https://www.firstlightoptics.com/scopetech-telescopes/scopetech-stl-80a-maxi-80mm-f15-classical-refractor.html

I'm hoping to do some white light solar observing as well so that's good news. 

I'm not expecting something outstanding tbh on the moon or planets with such a short focal length. Just enough so I can actually see some slight detail. 

Thanks for the help, looks like this scope is definitely in the running.

Adam

[Alkaid]

I have an st102.  Does low power star fields extremely well. It’s a sky-surfer this one, the larger objects such as M31 and M45 are good at x20, especially from a dark site.  Moon is awash with CA, don’t let anyone fool you into believing it’s a general purpose scope...cos it’s just not geared for solar system use and I daresay that the figure of the lens, while acceptable at low power, does not cut the mustard at higher powers.  (Being F5 doesn’t help either). I find about x50 to be the max with mine.  If you fancied something general purpose then the Apo’s are the way to go.

[MalcolmM]

I had an St102 and thought it was grab and go untill I bought a 60mm scope. 60mm and an appropriately small tripod is a one handed out and observing in 10 seconds grab n go. 100mm with the necessary larger tripod is just more awkward to manoeuvre out doors and carry. But I appreciate that everyone has a different take on what is grab n go size

Malcolm

[Aaf146]

58 minutes ago, MalcolmM said:

I had an St102 and thought it was grab and go untill I bought a 60mm scope. 60mm and an appropriately small tripod is a one handed out and observing in 10 seconds grab n go. 100mm with the necessary larger tripod is just more awkward to manoeuvre out doors and carry. But I appreciate that everyone has a different take on what is grab n go size

Malcolm

I'm just looking for something much easier to take out, when I haven't got as long, than my 8" (with cool down etc). That's why I was thinking of the 70mm ed, 80 is a little bit out of my price range unless I find a decent deal 2nd hand (which I am still looking at) but fingers crossed. 

If not I will probably go with the 100.

[Aaf146]

1 hour ago, Alkaid said:

I have an st102.  Does low power star fields extremely well. It’s a sky-surfer this one, the larger objects such as M31 and M45 are good at x20, especially from a dark site.  Moon is awash with CA, don’t let anyone fool you into believing it’s a general purpose scope...cos it’s just not geared for solar system use and I daresay that the figure of the lens, while acceptable at low power, does not cut the mustard at higher powers.  (Being F5 doesn’t help either). I find about x50 to be the max with mine.  If you fancied something general purpose then the Apo’s are the way to go.

I'm by no means a perfectionist as I've only used cheap refractors and reflectors up to now so a bit of CA won't bother me but might have a look if my local observatory has a few different variants to try before I make a definite decision

[Dan_Paris]

7 hours ago, Aaf146 said:

Hi guys, I have an 8" dob but am in the process of looking for a nice grab and go scope.

 

A 8" dob is very quick to set up, do you need something smaller and lighter ? 

 

In that case, if your budget is limited, you could build a travel dob mount for your mirror, something like this

 

https://www.webastro.net/forums/topic/193553-strock-2001000/

 

 

 

 

 

[Merlin]

What about a 130/f.5 Newt on a light alt/az?

 

 

[vlaiv]

https://www.firstlightoptics.com/evostar/sky-watcher-evostar-90-660-az-pronto.html

Do note that Skywatcher models will be more expensive due to announced 10-15% price increase in new batches. Current prices will last with current stock.

Above scope is nice compromise in everything - price, aperture, F/ratio and hence color aberration, weight ...

I personally only object it having 1.25" focuser instead of 2" (which 100mm models have).

Have owned st102 and it is not all around scope. CA is just too large for any serious higher power viewing. It itself might not bother you - but it simply blurs high power detail. 100mm can show quite a bit detail on planets / moon - but not so with st102.

Bresser ar102xs has similar amount of CA as st102. Although it has ED glass - it performs similarly to st102 because of faster F/4.6 ratio (which is hard on eyepieces).

Here is nice comparison between two scopes (and third one for good measure):

http://interferometrie.blogspot.com/2017/06/3-short-achromats-bresser-ar102xs.html

102/660 is the best due to it being slowest.

90/660 is faster than this still (at expense of some aperture).

In any case - you can control amount of CA for high power viewing by using aperture mask. Here scope with largest focal length has an edge. 90/660 can be easily turned into F/10 instrument by using 66mm aperture mask (and it will have similar performance on planets as for example 70mm ED from SW).

[Aaf146]

3 hours ago, Dan_Paris said:

 

A 8" dob is very quick to set up, do you need something smaller and lighter ? 

 

In that case, if your budget is limited, you could build a travel dob mount for your mirror, something like this

 

https://www.webastro.net/forums/topic/193553-strock-2001000/

 

 

 

 

 

Yeah, it's easy to carry outside, but it takes time to cool down. Plus I can barely fit it in my car so am looking for something smaller and lighter as you say.

Plus collimating it is a pain every time I go out with it.

[Lee_P]

The Sky-Watcher Evostar-90/660 that vlaiv linked to is a good choice. I reviewed it here.

[Aaf146]

28 minutes ago, vlaiv said:

https://www.firstlightoptics.com/evostar/sky-watcher-evostar-90-660-az-pronto.html

Do note that Skywatcher models will be more expensive due to announced 10-15% price increase in new batches. Current prices will last with current stock.

Above scope is nice compromise in everything - price, aperture, F/ratio and hence color aberration, weight ...

I personally only object it having 1.25" focuser instead of 2" (which 100mm models have).

Have owned st102 and it is not all around scope. CA is just too large for any serious higher power viewing. It itself might not bother you - but it simply blurs high power detail. 100mm can show quite a bit detail on planets / moon - but not so with st102.

Bresser ar102xs has similar amount of CA as st102. Although it has ED glass - it performs similarly to st102 because of faster F/4.6 ratio (which is hard on eyepieces).

Here is nice comparison between two scopes (and third one for good measure):

http://interferometrie.blogspot.com/2017/06/3-short-achromats-bresser-ar102xs.html

102/660 is the best due to it being slowest.

90/660 is faster than this still (at expense of some aperture).

In any case - you can control amount of CA for high power viewing by using aperture mask. Here scope with largest focal length has an edge. 90/660 can be easily turned into F/10 instrument by using 66mm aperture mask (and it will have similar performance on planets as for example 70mm ED from SW).

Thanks for the detailed reply. 1.25" isn't a complete deal breaker as most of my EPs are that size. I only have 1 2" and I don't think it'd work well with such a fast scope anyway. 

[Aaf146]

49 minutes ago, Merlin said:

What about a 130/f.5 Newt on a light alt/az?

 

 

Tbh I am hoping to get a refractor as they don't require collimating, among other things. Plus it is getting a little on the large side for me as my small setup.

Thanks anyway

Adam