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Sumerian Dobsonians

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#1 25585

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Posted 22 August 2019 - 11:24 AM

Sumerian is a Dutch company that makes lightweight truss Dobs using GSO or TS Quartz mirrors.

 

Has/does anyone here in CN have experience with them, particuarly the Alkaid models?

 

https://www.sumerianoptics.com/


Edited by 25585, 22 August 2019 - 11:26 AM.


#2 sg6

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Posted 22 August 2019 - 12:11 PM

Believe Ed, aeajr, has one and even think it is the 10".

Michael runs and operates Sumarian. If you buy a "standard" one I believe they are now sold through TS. The bigger ones he still produces at somewhere close to Schipol airport - BUT you have to supply the mirror.

 

He had a bad experience with a batch of mirrors and pulled out of doing/supplying the whole lot himself. If memory is right he made the full item but GSO had a bad batch and he got some. Therefore he was responsible for the overall product, and had a number of problems having to replace the mirrors at his cost.

 

So he stopped producing the sort of smaller more budget minded ones, and I didn't get one in time.

 

Could get a day trip to Schipol and visit I suppose. Easy enough. Certainly if you get one I would.



#3 junomike

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Posted 24 August 2019 - 07:46 AM

Review



#4 stargazer193857

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Posted 25 August 2019 - 01:57 PM

Sumarian makes beautiful scopes.

#5 BGazing

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Posted 11 September 2019 - 07:22 AM

Anyone has 12in f/5 Alkaid? Would love to hear how it handles the weight of a Paracorr.



#6 Astrojedi

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Posted 11 September 2019 - 08:48 AM

A prior CN thread on these scopes: https://www.cloudyni...nch-telescopes/

#7 aeajr

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Posted 11 September 2019 - 09:04 AM

Believe Ed, aeajr, has one and even think it is the 10".
Michael runs and operates Sumarian. If you buy a "standard" one I believe they are now sold through TS. The bigger ones he still produces at somewhere close to Schipol airport - BUT you have to supply the mirror.

He had a bad experience with a batch of mirrors and pulled out of doing/supplying the whole lot himself. If memory is right he made the full item but GSO had a bad batch and he got some. Therefore he was responsible for the overall product, and had a number of problems having to replace the mirrors at his cost.

So he stopped producing the sort of smaller more budget minded ones, and I didn't get one in time.

Could get a day trip to Schipol and visit I suppose. Easy enough. Certainly if you get one I would.


Just saw this. No, I don't have one of these. I have an Apertura 12" Dob.

#8 25585

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Posted 14 September 2019 - 07:24 AM

A shame the Canopus is no longer made.



#9 sixela

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Posted 14 September 2019 - 06:37 PM

Anyone has 12in f/5 Alkaid? Would love to hear how it handles the weight of a Paracorr.

The f/5 10" are really not Paracorr friendly. It's not impossible to use a Paracorr in those, but relying on the tension cords makes the movements less subtle (not to mention that without counterweights the whole scope can tip over close to the horizon).

 

Last I saw therm, the 12" f/5s were neutral without a Paracorr, so I'd advise to see if you can put a fairly hefty counterweight on the mirror plate to avoid having to use the tension cords. But perhaps the balance changed recently (since it's easier to add a little weight at the top than a lot of weight at the bottom).

 

The f/4s and the larger models are usually balanced for use with a Type 2 Paracorr, in the recent examples I saw, and you actually need the tension cords to pull them down if you don't use one.

 

A friend ordered a custom fast 16" Alkaid and told Michael to cut the poles for non-Paracorr use and to tweak the balance for non-Paracorr use. Michael refused, cut the poles for the Paracorr Type 2, and then told the customer that he'd give him a second set of poles for free if necessary. Only one night with a Paracorr convinced that customer to buy a Paracorr  ;-).


Edited by sixela, 14 September 2019 - 06:39 PM.

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#10 BGazing

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Posted 15 September 2019 - 02:35 AM

The f/5 10" are really not Paracorr friendly. It's not impossible to use a Paracorr in those, but relying on the tension cords makes the movements less subtle (not to mention that without counterweights the whole scope can tip over close to the horizon).

 

Last I saw therm, the 12" f/5s were neutral without a Paracorr, so I'd advise to see if you can put a fairly hefty counterweight on the mirror plate to avoid having to use the tension cords. But perhaps the balance changed recently (since it's easier to add a little weight at the top than a lot of weight at the bottom).

 

The f/4s and the larger models are usually balanced for use with a Type 2 Paracorr, in the recent examples I saw, and you actually need the tension cords to pull them down if you don't use one.

 

A friend ordered a custom fast 16" Alkaid and told Michael to cut the poles for non-Paracorr use and to tweak the balance for non-Paracorr use. Michael refused, cut the poles for the Paracorr Type 2, and then told the customer that he'd give him a second set of poles for free if necessary. Only one night with a Paracorr convinced that customer to buy a Paracorr  ;-).

Thank you, now that was VERY informative. Sounds like f/4 is a sure shot (but then it has to be a BK7) mirror and f/5 is...maybe. 

I know it is an evolving design and apparently the balance issues have been tweaked a bit (you cannot tweak laws of physics). I reckon a few earlier balance issues were caused by people ordering thin and light mirrors, not enough heft below.

A user on the SGL bought f/5 model and uses it without Paracorr with no balance problems, one cord for lighter EPs, two cords for heavier (Michael suggested f/4 initially 'for better stability', so that is something along what you have just written). Still, Paracorr 2 plus Nag 6 equals one Ethos, does it not?



#11 Roragi

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Posted 15 September 2019 - 03:01 AM

We must recognize that they are very beautiful scope and Alkaid's idea to travel by plane is really good. I have only seen two models 14 "alkaid really very light and transportable, but with some possible improvements, the pipes are really thin and this causes great bending when using heavy eyepieces, in addition to only having a ring in secondary cage. It is very susceptible to wind.

 

A friend ordered a canopus structure, of the two models I like this one more, it is simply more robust, the thicker bars and let's say it has better wind stability. Its points weak the primary cell and the secondary spider, you can not correct the side off set by being fixed to the secondary cage.

 

Now there are models that are not manufactured and others that, like the 10 '' that I stop manufacturing due to balance problems, honestly too expensive for such a small scope.

Even with all my criticisms, it is one of the most beautiful scopes I know of the best known artisans.



#12 sixela

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Posted 15 September 2019 - 06:11 PM

Michael did use to make furniture for a living, so his woodworking skills are a lot better than mine ;-).



#13 Moravianus

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Posted 17 September 2019 - 02:05 AM

Sumerian makes beautiful scopes.

https://www.cloudyni...zambuto-mirror/



#14 sixela

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Posted 17 September 2019 - 02:11 AM

Curved spider Canopus — they don't come more rare than that...

#15 BGazing

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Posted 17 September 2019 - 03:41 AM

Like the natural varnish finish, not fond of that universally black varnish nowadays.




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