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Old 01-03-2021, 08:20 PM
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Malang_Darwish
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Seeking recommendations on an 8"-10" Dob

Hello all!

I'm new to this forum, and relatively new to the hobby. My current equipment is listed in my signature. First and foremost, thank you for having me here, I look forward to becoming a part of this community.

Anyway, I recently got to thinking that I should upgrade to a better telescope for visual observing (before I decided I wanted to go down the astrophotography path; that's a post for a different part of the forum).

I settled on a Dob, and was thinking of the Skywatcher options. The collapsible options in particular appeal to me. However, they are, first, out of stock, and second, seem to be the only options.

Here's the two that I was thinking of:

Sky-Watcher 10″ Collapsible Dobsonian

Sky-Watcher 8″ Collapsible Dobsonian

What I'd like to know
  1. What other options are there for collapsible Dobs?
  2. How do the different brands compare to one another?

Thank you all in advance for your help!

Best,

Malang

P.S. I just realised this might be posted in the wrong part of the forum, if so, could a Mod please let me know? Thanks!
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Old 01-03-2021, 08:35 PM
Rerouter (Ryan)
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For a newtonion, there is not many improvements to be made between one or another, I would hazard a guess some brands hold collimation better than others, but that can be worked around if needed,

There are other options. e.g. saxon through bintel, but they also seem to have stock issues with the collapsables.

If I was to set a solid difference, that could be the focuser, and that it can reach focus with a camera, a number of visual newtonians can struggle with with this (found out the hard way my self)

As the focual length is the same, I should point out there is a tradeoff when it comes to F ratio, the lower the F ratio, the more Coma comes in to play, and the better you have to focus it, but you get more light for the same exposure time,

And finally you can use a Dob for astro, however it uses a device called a rotator, to correct for the rotation in the sky.

I'm kind of curious what drew you to a collapsible. there is no real weight saving between the 2 options, or is it more how heavy the individual pieces are? as the tube does seperate from the base.
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Old 01-03-2021, 09:16 PM
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Malang_Darwish
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Quote:
Originally Posted by Rerouter View Post
For a newtonion, there is not many improvements to be made between one or another, I would hazard a guess some brands hold collimation better than others, but that can be worked around if needed,

There are other options. e.g. saxon through bintel, but they also seem to have stock issues with the collapsables.

If I was to set a solid difference, that could be the focuser, and that it can reach focus with a camera, a number of visual newtonians can struggle with with this (found out the hard way my self)

As the focual length is the same, I should point out there is a tradeoff when it comes to F ratio, the lower the F ratio, the more Coma comes in to play, and the better you have to focus it, but you get more light for the same exposure time,

And finally you can use a Dob for astro, however it uses a device called a rotator, to correct for the rotation in the sky.

I'm kind of curious what drew you to a collapsible. there is no real weight saving between the 2 options, or is it more how heavy the individual pieces are? as the tube does separate from the base.
Thank you for your reply! I'll have to check those options out on Bintel, I did notice in general that stock levels are... non-existent for a lot of stuff at the moment.

The main reason that I was drawn to a collapsible is just to save space for storage, and to make it a bit easier to transport when collapsed.

Would it be practical to use a Dob for astrophotography?

You mentioned some have focal length issues, did you mean that the Saxon one's don't have that issue?

I was thinking of getting a separate refractor for astrophotography, to be honbest: http://www.iceinspace.com.au/forum/s...d.php?t=189787
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Old 01-03-2021, 09:22 PM
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Malang_Darwish
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I did also just notice this, and I'm very tempted by it:

6″ VIRTUOSO GTI COLLAPSABLE DOBSONIAN
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Old 01-03-2021, 09:39 PM
Rerouter (Ryan)
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A dob is fine for astrophotography, provided you add a rotator, this would likely be combined with some motors for a given mount to keep it pointed at the same object in the sky, essentially a tracking dob mount has the night sky appear to rotate, and the rotator cancels that out, something like an onstep controller is not a bad thing to keep in mind for an aftermarket tracking option.

The issue was not with focal length, more the F ratio which is focal length / apeture size, as they are the same focal length, the 10" is faster, so it takes images in a shorter time, at the trade off for a bit more need for a coma corrector if thats your preference, (not as big an issue with visual), and a slightly smaller ideal focus window, (again not as big an issue with visual)

This is kind of just a principle of all telescopes, the higher the F ratio, the slower / darker things are, but the more relaxed focusing it is, at F/4.7 with the 10" guy its not an issue, sorry if I went driving you down the wrong trail, as most newtonions are about F/5

A smaller refector can work, certainly more portable, however for larger magnifications, a large apeture is king, e,g, if you want to do planetary, for deep sky, either work, just the higher the F ratio, the longer it takes for the same image brightness,
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Old 01-03-2021, 09:44 PM
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Quote:
Originally Posted by Rerouter View Post
A dob is fine for astrophotography, provided you add a rotator, this would likely be combined with some motors for a given mount to keep it pointed at the same object in the sky, essentially a tracking dob mount has the night sky appear to rotate, and the rotator cancels that out, something like an onstep controller is not a bad thing to keep in mind for an aftermarket tracking option.

The issue was not with focal length, more the F ratio which is focal length / apeture size, as they are the same focal length, the 10" is faster, so it takes images in a shorter time, at the trade off for a bit more need for a coma corrector if thats your preference, (not as big an issue with visual), and a slightly smaller ideal focus window, (again not as big an issue with visual)

This is kind of just a principle of all telescopes, the higher the F ratio, the slower / darker things are, but the more relaxed focusing it is, at F/4.7 with the 10" guy its not an issue, sorry if I went driving you down the wrong trail, as most newtonions are about F/5

A smaller refector can work, certainly more portable, however for larger magnifications, a large apeture is king, e,g, if you want to do planetary, for deep sky, either work, just the higher the F ratio, the longer it takes for the same image brightness,
Thanks so much! More to keep in mind... I think it may be hard for me to find a jack of all trades, and I may end up with multiple telescopes, perhaps one for visual and one for astrophotography to start with
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Old 01-03-2021, 10:35 PM
SkyWatch (Dean)
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Hi Malang,
I notice that Andrews seem to have a Sky-Watcher 10" collapsible dob in stock. http://www.andrewscom.com.au/optical-telescopes
They have a dodgy website, but if you go to "Skywatcher" and scroll down you should find it...
All the best,

Dean
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Old 02-03-2021, 12:07 AM
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Malang_Darwish
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Quote:
Originally Posted by SkyWatch View Post
Hi Malang,
I notice that Andrews seem to have a Sky-Watcher 10" collapsible dob in stock. http://www.andrewscom.com.au/optical-telescopes
They have a dodgy website, but if you go to "Skywatcher" and scroll down you should find it...
All the best,

Dean
Thanks Dean I'll have to check that out!!!
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Old 02-03-2021, 07:18 PM
highlander2287 (Brett)
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Hi,
I am no expert and still basically a beginner, however I would just like to say that I purchased a 10" skywatcher goto collapsible dob for my viewing and I have been very happy with it since its purchase. I am still to get into astrophotography with it,but I don't think you would be disappointed with one if you bought one.
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Old 05-03-2021, 03:50 PM
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Malang_Darwish
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Quote:
Originally Posted by highlander2287 View Post
Hi,
I am no expert and still basically a beginner, however I would just like to say that I purchased a 10" skywatcher goto collapsible dob for my viewing and I have been very happy with it since its purchase. I am still to get into astrophotography with it,but I don't think you would be disappointed with one if you bought one.
That's really good to know, and thank you so much for sharing your experiences with that telescope. I can't wait to get my hands on one!
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