8 inch Dobsonian - Saxon, Skywatcher, OzScopes, Bintel

[ManUtdFans]

HI,

Searched thru 8 inch Dobsonian found the price will be ~$500 for the about brands.
Saxon, Skywatcher and Ozscopes have similar build and outlook.
For Bintel the handle to lock is different.

Not sure which one is better or the same?

[Allan_L]

Only my opinion, but
Of these, I would go skywatcher.
and in particular, their flex tube dobsonian.

I believe it is the only one (of these) with Pyrex a mirror (I believe the others use BK7 glass in mirrors this size).
WHY:
Well reportedly, pyrex is superior due to:
"Telescopes using mirrors made of BK7 have more than twice the heat expansion than mirrors made of Pyrex. This means that in practice, a telescope with a Pyrex mirror provides us with a significantly better image during the heat expansion phase than a BK7."

Some of the other brands use Pyrex only in their mirrors of bigger than 10"

[ManUtdFans]

Is there a way to check if Skywatcher mirror made of Pyrex?

[mental4astro]

Saxon, Skywatcher, Celestron, Tasco, Jason, Konus - these and many others are owned by the one Chinese parent company, Synta. All their scopes are the same per model.

Bintel branded scopes are GSO in origin, a Taiwanese firm.

Andrews Communications also sells GSO scopes. Their 8" dob is $449, & is the same scope sold by Bintel.

Quality difference between these two? Bugger all really. These are mass produced instruments, so each will have excellent examples & poor ones. On the whole, it just comes down to your own preference.

I have to differ with you here for once Allan, :). Pyrex vs BK7 is more significant in apertures larger than 12", & more so for imaging than visual for the time that the cooling process happens over, & then no more problem (if the differences are really that significant). Any issues with expansion is quickly dealt with by a little fan if it really concerns you if you have a solid tube scope. My 17.5" has the primary completely exposed, & any cooling issues here in Oz, really is not significant enough to warrant complicating things with a fan, & the cooling that happens while I set up is as far as I consider 'cooling' to happen, & while I'm waiting for the sky to darken. I think we tend to fixate too much on cooling our scopes if visual is all we use our scopes for. Even a solid tube is a metal tube that dissipates heat very quickly, & the rear of the tube is not a sealed unit, making cooling really even less of the problem we make it out to be. Dew is more problematic than cooling as far as I'm concerned. We fan our mirrors to cool them & then heat them to keep dew off - nuts!

[Shark Bait]

I am sure that you will enjoy the views through a Sky Watcher, Saxon, Bintel / GSO 8' Dobsonian Telescope. They will all give you really nice views, with the Bintel / GSO having a higher spec focuser. Bite the bullet Alan, the night sky awaits. :thumbsup:

[Allan_L]

Fair enough Alex and Stu, but Alan did ask for any differences.

Where in Sydney are you, Alan?
Why not come up to Mangrove Mountain this Saturday evening for a viewing night and you can look through several different brands and sizes and speak to the owners?

All welcome, no charge, dark skies.
or if you are more west than north, go to Katoomba with Alex

always best to try before you buy.
and talking to users is invaluable

[Astro_Bot]

Close, but not quite. :)

Synta and Saxon are not the same company. Their Dobs and EQ mounts look identical (save colour) but Saxon doesn't do GoTo dobs and sells nothing larger than an HEQ5 on the EQ side. This may be for any of a number of reasons, but doesn't require ownership, e.g./including: one buys whole from the other; they both buy some or all components alike from a third supplier; they have a technology/product sharing deal; or, they use the same tubes but their own mirrors. Whatever the product distribution arrangement between them, they are not the same company. My guess would be that Saxon buys Dobs and EQ mounts from Synta, perhaps with some part substitution.

OzScopes looks like re-branded Saxon (or maybe Synta!). I don't know who owns OzScopes, but they don't appear to make anything themselves, i.e. they're just a reseller/re-brander.

Jason I know almost nothing about, but they seem to sell cheap rubbish, including some stuff "made by" Bushnell. Konus I don't know much about - except that Konus is Italian based and seems to make some of its own stuff, but probably not the telescope line - in that regard, I suspect both Jason and Konus are resellers/re-branders.

Tasco (Tasco Sales Australia) is not owned by Synta. They are the Australian SkyWatcher distributor (and of a lot of other products including Tasco and Bushnell). They appear to be a privately owned company. Tasco Worldwide (a US company that actually makes things, albeit probably in China) is not owned by Synta either - they are owned by a private equity firm (MidOcean Partners, who also own Bushnell), at least that's the last info I've seen. Tasco (in the USA) used to own Celestron many years ago, before Celestron was sold to Synta (when Tasco was going bankrupt) - this past association and some apparent product re-branding today (some Tasco branded 'scopes look like cheap stuff also sold uinder other brands) seems to confuse the issue. It's a convoluted history, but Tasco and Bushnell are pretty much one and the same now, but separate from Celestron (and Synta).

BTW, Orion (in the USA) sells Synta EQ mounts badged as Orion Atlas etc., but it's not owned by Synta either.

Synta does own Celestron, and, of course, uses the SkyWatcher brand.

Confused yet? :)

At least the Bintel/GSO relationship is fairly clear - Bintel re-brands GSO products.

---------

I think Allan's suggestion is a good one. As a beginner, though, you're probably not going to notice a difference between any of the same-sized Dobs, IMHO, save for some perhaps being better collimated (by the user) than others.

[ManUtdFans]

WOW, pretty complicated business associations among those brands !
What do you think which brands mirrors/lens will be better if I am going for 8 inch Dob?

Ah, Sat is new moon night, right?

[ManUtdFans]

Hi Allan,
I am at Sydney west, not sure how many people will be at Katoomba.

[mental4astro]

Yeah, complicated. I just learnt something new too. Ta astro-bot.

There really isn't any difference that you can do without actually testing each and every mirror. And, as an example, then you might find that a BK7 mirror might have a better figure than a Pyrex one, and then the difference in the material is only a cooling aspect, but once equalised there is no difference in performance. The vast majority of dobs from ANY of the brands listed in this thread will give a very good image.

The differences in material are not important. Really they are not. For being mass produced, the average quality of any of these is very, very good. Yes, every now and then one will be poor, and another exceptional, but this has nothing to do with one being Pyrex or BK7. What they ALL have as a common flaw is the particle board mount that they all use. These eventually fall victim to dew. But there are steps that can be taken to slow this from happening.

Like Allan said, I too would preference a GSO scope (Bintel falls in this case too) for the better standard focuser they use. GSO scopes also tend to be better priced too. The two main retailers of GSO scopes are Bintel (http://www.bintel.com.au/) and Andrews Communications (http://andrewscom.com.au/site-section-10.htm). The service provided and knowledge of both retailers is excellent. I have never had a problem they couldn't resolve for me, and these have been very rare.

At Katoomba we can have anywhere from 10 people to 20 people showing up. Enough numbers for you?

[mr bruess]

What they ALL have as a common flaw is the particle board mount that they all use. These eventually fall victim to water and moisture.
There should be a warning that these particle boards will fall apart in the wet.they should make the dob bases in water proof marine grade wood/ply.

[astro_nutt]

Hi Alan.
Regarding how you can if a mirror is made from Pyrex. Looking at the mirror from the side, if it's green, it's glass. If it's white-ish, it's Pyrex.
Cheers!

[barx1963]

Personally, in an 8" I would go the GSO/Bintel every time for a couple of reasons.
1. The focuser is a much better product without the bizarre Skywatcher system of adapters that constantly trip up new beginners here on IIS. I had the opportunity to play with the adapters last weekend while assisting with collimating a scope and it was very frustrating to say the least.
2. Usually cheaper!

As regards Mr Bruess's comment on the chip boards. I used my 12" GSO for several years including a lot of wet dewy nights and never had an issue. It was also left out at a couple of star parties where it rained, albeit under a shower tent and with a tarp underneath. I had taken the precaution of running some silicone along all the joints and also a line of superglue along all the edges to assist with the waterproofing. Marine ply is fine but it would push up the cost significantly.

With the pyrex vs BK7, one issue is that BK7 can present issues for re-coating. I was told this by Chi Qin when he was still doing re-coating, but why anyone would bother re-coating an 8" when a new one can be bought relatively cheaply. At larger apertures it could easily become an issue.

Cheers

Malcolm

[Quoll]

As the new owner of a DOB I’ve been reading this thread with interest, as I’m sure a lot of other new DOB owners have. In particular I was interested in what Alexander and mr bruess had to say about DOB bases not standing up to wet conditions because of their particle board construction.

Malcolm - thanks for the tips on waterproofing.

[AG Hybrid]

Epic thread resurrection.



Wouldn't worry too much about the particle board issue. Unless you regularly observe in a place of heavy dew, leave your scope in the rain or actually hose down your Dob mount. They should last some years. If you keep it dry. Should be fine.

[Steffen]

Neither would I. On my 5-year old DSO Dob there is no swelling, let alone falling apart of base components. I dare say they use a better grade of particle board that the cheap shelving you find at Bunnings.

If you're paranoid about it you can always paint the edges with diluted PVA glue before assembly.

Cheers
Steffen.

[raymo]

One factor to consider is that the skywatcher dobs despite their unpopular focuser and adaptor setup, are suitable for prime focus work, which is not the case with some other brands.[without either minor or major mods]. Worth checking the scope you select to see if it will reach focus,
raymo