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Are All Brand Name Dobsonians the Same?

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#1 Oscar56

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Posted 27 February 2013 - 11:41 PM

I am just getting started in this hobby, so far I have only binoculars, Nightwatch, CN and lots of cloud cover. But I have been doing plenty of reading on the internet and lots of window shopping on telescope sites for 8" and 10" Dobs.

Excluding hand built Dobsonians I am starting to suspect that all of the brand name Dobs are virtually the same. I am aware that they all start in 1 or 2 factories in China even if the paint job and labels may be different.

But are they really any different in optics and value? At the heart of a Dob is it not just a sono tube, parabolic mirror and 2ndary mirror? After that the various brands offer different EPs, focusers, target sights etc?

So if there is a "high end" of the 8" and 10" Dobs is it a function of the peripherals or does one brand use better mirrors as their starting point?

#2 Jason D

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Posted 27 February 2013 - 11:54 PM

You have custom made and mass produced made dobs. You are asking about the mass produced dobs. I would say you got it right. Most are more or less the same in terms of quality.

#3 kfiscus

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Posted 28 February 2013 - 12:11 AM

The Chinese scopes are now steel tubes. As the OP has written, the price differences are from the accessories included with the rig. The optics tend to be incredible values. I currently own a 4.5, 6, 10, and two 12s.

#4 Oscar56

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Posted 28 February 2013 - 12:16 AM

You have custom made and mass produced made dobs.


And what is it about the custom made units that they command such a significant price differential?

#5 Jason D

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Posted 28 February 2013 - 12:22 AM

You have custom made and mass produced made dobs.


And what is it about the custom made units that they command such a significant price differential?


Better design, attention to details, and quality components -- especially optics.

#6 Oscar56

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Posted 28 February 2013 - 12:29 AM

Jason:

Your signature refers to an Orion X10? What are the premium optics? Better quality mirror(s)?

#7 Jason D

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Posted 28 February 2013 - 12:52 AM

Jason:

Your signature refers to an Orion X10? What are the premium optics? Better quality mirror(s)?


Correct. I replaced my stock secondary and primary mirrors with premium mirrors. The primary mirror was hand made by a reputable optician. There is a difference in image quality at the eyepiece but the difference is subtle. The cost of the replacement was almost twice the cost of my original XT10.

#8 Jon Isaacs

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Posted 28 February 2013 - 08:15 AM

Better design, attention to details, and quality components -- especially optics.



Generally the optics are better but a great deal of effort and cost goes into the structure itself. Premium Dobsonians are made high quality plywood rather than particle board and steel and constructed using custom cabinetry/furniture making techniques. The bearings are big and the motions super smooth and the mounts stable.

I have both some custom built dobs as well as a 10 inch F/5 GSO Dob. I enjoy them all but the custom scopes do work better.

Jon

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#9 nirvanix

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Posted 28 February 2013 - 10:55 AM

I'll just chime into the mix with the statement that these days you are likely to have a very positive experience with the commercial dobs. They have improved a lot of the mechanical annoyances that the early versions had, and as many satisified CNers will attest , the optics are typically good. Having said that, if you are an enthusiast and can spare the coin, you would appreciate a premium scope. There's a 20 inch quartz mirror dob over at astromart that I'm salivatin' over!

#10 johnnyha

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Posted 28 February 2013 - 01:34 PM

The Teeter STS 8" and 11" dobs are a good example of a custom scope where something similar to the typical mass-produced tube dob structure has been built, but with super quality materials by a master craftsman. Then Rob Teeter offers the buyer the choice of using a typical mass-produced GSO mirror or for a higher price, a custom mirror.

#11 Oscar56

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Posted 28 February 2013 - 02:46 PM

Thanks to everyone who participated in this thread. I will be weighing the options of investing in a 8" or 10" later this year. My budget (nor my wife) will not allow me to invest in a custom scope, but I am getting a better idea on what to look for when comparing different brand name dobs and what improvements to make over time.

#12 Jon Isaacs

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Posted 28 February 2013 - 04:05 PM

Thanks to everyone who participated in this thread. I will be weighing the options of investing in a 8" or 10" later this year. My budget (nor my wife) will not allow me to invest in a custom scope, but I am getting a better idea on what to look for when comparing different brand name dobs and what improvements to make over time.


I think that the modern Asian commercial Dobsonians are quite good and don't need a lot of improvements. I think you get more value for your dollar with the GSO Dobs than the Synta Dobs, the basic scopes are essentially the same but the GSO Dobs (Astro-Tech, Zhumell, Apertura) have better outfitted and have better accessories. In particular, the standard 2 speed GSO focuser is simple but very effective.

The bases are made from particle board but is durable and long lasting. My 10 inch GSO is more than 10 years old. I bought it when it was less than a year old but it had been left out in the rain one night... :) The base shows the wear and tear of the thousands of miles it has traveled but it's solid.

Jon

#13 Oscar56

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Posted 28 February 2013 - 04:43 PM

[/quote]

I think you get more value for your dollar with the GSO Dobs than the Synta Dobs, the basic scopes are essentially the same but the GSO Dobs (Astro-Tech, Zhumell, Apertura) have better outfitted and have better accessories. In particular, the standard 2 speed GSO focuser is simple but very effective.

Jon [/quote]

Jon:

As I recall Synta owns Celestron etc. GSO is another manufacturer? What other name brands are manufactured by GSO?

To bring the GSO versions that you listed north of the border will incur additional shipping and brokerage costs which may negate the value of the better accessories.

#14 johnnyha

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Posted 28 February 2013 - 11:31 PM

The Teeter STS 8" and 11" dobs are a good example of a custom scope where something similar to the typical mass-produced tube dob structure has been built, but with super quality materials by a master craftsman. Then Rob Teeter offers the buyer the choice of using a typical mass-produced GSO mirror or for a higher price, a custom mirror.


Wow, looks like Rob has just changed to using mirrors by Alan Raycraft of Antares Optics as standard instead of GSO... :cool:

#15 Deep13

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Posted 01 March 2013 - 12:40 AM

Except for small, custom vendors, the answer is yes. Optically, they are all the same. And by the "the same," I mean within their range of quality control variances.

#16 KerryR

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Posted 01 March 2013 - 10:33 AM


Wow, looks like Rob has just changed to using mirrors by Alan Raycraft of Antares Optics as standard instead of GSO... :cool:


I'm glad to hear Alan Raycraft is still around. He refigured my 8" Newtonian (Asian) mirror several years ago, as part of my "HPN" scope from the now defunct Anttlers Optics. Shortly after that, his website declared he'd only be doing OEM optics and would no longer be providing consumer services. I was wondering what had become of him.

#17 Jon Isaacs

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Posted 01 March 2013 - 10:45 AM

I'm glad to hear Alan Raycraft is still around. He refigured my 8" Newtonian (Asian) mirror several years ago, as part of my "HPN" scope from the now defunct Anttlers Optics. Shortly after that, his website declared he'd only be doing OEM optics and would no longer be providing consumer services. I was wondering what had become of him.



I also wondered what had happened to Alan. He refigured my 12.5 inch F/4.06 for me several years ago and then dropped out of sight. Good to know he is still around.

I think he did the first Starmaster Oak Classics.

Jon

#18 Jerry-rigged

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Posted 01 March 2013 - 11:43 AM

[quote name="Oscar56"][/quote]

I think you get more value for your dollar with the GSO Dobs than the Synta Dobs, the basic scopes are essentially the same but the GSO Dobs (Astro-Tech, Zhumell, Apertura) have better outfitted and have better accessories. In particular, the standard 2 speed GSO focuser is simple but very effective.

Jon [/quote]

Jon:

As I recall Synta owns Celestron etc. GSO is another manufacturer? What other name brands are manufactured by GSO?

To bring the GSO versions that you listed north of the border will incur additional shipping and brokerage costs which may negate the value of the better accessories. [/quote]


Meade Lightbridge truss scopes are also GSO, I think.

#19 Oscar56

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Posted 01 March 2013 - 11:46 AM


[/quote]

I'm glad to hear Alan Raycraft is still around. He refigured my 8" [/quote]

What does a refiguring consist of?

#20 KerryR

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Posted 01 March 2013 - 12:29 PM

[quote name="Oscar56"]
[/quote]

I'm glad to hear Alan Raycraft is still around. He refigured my 8" [/quote]

What does a refiguring consist of? [/quote]

Bench testing the mirror, asessing the accuracy of the paraboloidal surface, removing coatings, and adjusting the accuracy of the curve in the surface of the mirror to bring it closer to theoretical accuracy.

#21 Mike B

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Posted 01 March 2013 - 01:00 PM

...and adjusting the accuracy of the curve in the surface of the mirror...



Something like this.

Can always be done down the road, years later... as the budget permits.

#22 KerryR

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Posted 01 March 2013 - 01:09 PM

...and adjusting the accuracy of the curve in the surface of the mirror...



Something like this.

Can always be done down the road, years later... as the budget permits.


I'd add that most of the time, re-figuring is done by hand, rather than machine, with a human doing something similar to the image linked above...

#23 Deep13

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Posted 02 March 2013 - 02:16 AM

So where can one get an entry-level Dob with a mirror that figured properly the first time?

#24 Jon Isaacs

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Posted 02 March 2013 - 07:34 AM

So where can one get an entry-level Dob with a mirror that figured properly the first time?


Most entry level Dobs have mirrors that are plenty good, good enough that the mirror will rarely be the limiting factor, rather, the limiting factors will be the seeing, the thermal condition of the scope and/or the skill of the observer.

Jon

#25 nirvanix

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Posted 02 March 2013 - 07:56 AM

So where can one get an entry-level Dob with a mirror that figured properly the first time?


Most entry level Dobs have mirrors that are plenty good, good enough that the mirror will rarely be the limiting factor, rather, the limiting factors will be the seeing, the thermal condition of the scope and/or the skill of the observer.

Jon


Well said Jon.






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