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SkyWatcher’s 20" goto truss dob!

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#126 wolfli

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Posted 03 April 2017 - 06:23 PM

finally appears on the website

 

http://www.skywatche...ate-18-synscan/

http://www.skywatche...ate-20-synscan/


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#127 Zamboni

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Posted 03 April 2017 - 06:32 PM

It's been on the global site for a long time. Still not on the USA site.

#128 wolfli

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Posted 08 April 2017 - 07:45 PM

http://skywatcherusa...russ-dobsonian/

 

Now they are up!


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#129 niallk

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Posted 09 April 2017 - 12:47 AM

I notice that the new pics on the website (and in S&T magazine) do not show the additional braces on the trusses of the 20": are they no longer required? (ie the design has been modified?)

#130 skyward_eyes

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Posted 09 April 2017 - 01:10 AM

The braces come included with all Stargate dobsonians, as well as the shroud. 


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#131 wolfli

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Posted 09 April 2017 - 05:57 AM

Would it be possible to provide a measurement of the sizes for transportation? That would be really helpful for small car owners.


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#132 Starman1

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Posted 09 April 2017 - 10:03 AM

The braces come included with all Stargate dobsonians, as well as the shroud. 

It looks like the focuser could be mounted on the other side merely by rotating the top ring when assembling, but the finder would then be underneath the focuser.

Though that might not be a problem with such a large scope, is it possible to remount the finder above the focuser should a user want the focuser on the other side?

I suppose a user could always drill new holes......

 

Edit: Ah, I see the focuser is not exactly on the side, so reversing the upper ring won't work at all.  Too bad.


Edited by Starman1, 09 April 2017 - 10:07 AM.


#133 davidmclifton

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Posted 09 April 2017 - 09:47 PM

I saw and played with the 20" GOTO model at NEAF. Really interested, but concerned about the mirror given I have never seen anything quite like that. My 2 cents is that SkyWatcher USA needs to get a well known large dob observer to do a serious and honest review of these things in action and get it posted up here, S&T etc. I love the idea of it, but with some of the design being significantly different from other offerings in this space I know folks like me have to be sitting there thinking "Looks cool, where's the real review so I know I'm not flushing $8k down the toilet?"



#134 Pinbout

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Posted 09 April 2017 - 10:17 PM

https://www.youtube....aZAJvs&index=17

 

how about just bring it outside so everyone gets to see Jupiter instead just lookin pretty inside. lol.gif

 

just think how quickly those mirrors cool.

 

they're pretty sturdy, stiff in a good way.

 

the only concern I would have with that money is mirror quality and one person's review of one unit isn't enough.

 

the 2ndry support looks weird cause its way off centered, like not on a typical .4/.6 radius.

 

luv to bench test those optics.



#135 wolfli

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Posted 09 April 2017 - 11:00 PM

I also looked into this scope in a lot of details today at NEAF. My interpretation of their mirror structure is that it is a untra-thin mirror with a glass mirror float. This may well work better than a traditional mirror float.

 

About the structure: It is nice and rigid once everything is properly locked down. Hotech kindly lent me one of their laser collimator and I was able to check whether the collimation shifts from horizon to zenith. It does. If you started from the horizon fully collimated, the laser dot will drift to the second or the third ring at zenith. Apparently mostly from the primary mirror moving a little bit. But it is a very small drift. The mirror turns only 0.03 degrees. My obsession 12.5" f/5 have a similar amount of shift.

 

About the movement. It is pretty good. What was surprising is that the goto version actually feels smoother when moved manually, compared to the manual version. It was better than my previous Orion XT12i but maybe, probably a little less consistent than an Obsession. The included counterweight system is really cool.


Edited by wolfli, 10 April 2017 - 08:13 AM.


#136 Spacefreak1974

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Posted 10 April 2017 - 08:03 AM

Maybe contact this guy on youtube at the Texas Star party? https://www.youtube....h?v=oyc7p16vvd0

 

or this guy in Korea. It looks like he responds to comments on his videos in English

https://www.youtube....h?v=h8o2iL112jk


Edited by Spacefreak1974, 10 April 2017 - 08:06 AM.


#137 radicell2

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Posted 10 April 2017 - 08:45 AM

I saw and played with the 20" GOTO model at NEAF. Really interested, but concerned about the mirror given I have never seen anything quite like that.

I fused up a 12 inch f/6 conical ribbed layout mirror back in 1988 that is like the Starwatcher blanks.Works fine and is still in one piece.If they get the anneal right there shouldn't be a problem.Optical quality is unknown so far.

Biggest advantage is the ultra quick cool down,about 15 minutes to ambient.Local club had a full thickness 12 incher f/6 kept in a roll off hut.On a hot July day took from 8 pm to around 11pm before the heat currents stop coming off the mirror.

Did consider manufacturing conical back in the late '80's but the labour costs - kiln needs to watched all the time -killed the idea for mass production.Figured China was the only place with low wages that might make a go of it.

Ric


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#138 MSWcdavis

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Posted 16 April 2017 - 04:50 PM

very fine looking scope - targeting the premium side of things it seems?  But these are more portable?

 

comparing to some other premium dobs - what are everyone's thoughts on respective value and strengths of these skywatcher stargates?

 

 8640 for 18 inch starstructure GOTO

 

 9600 for 20 inch starstructure GOTO

 

 9100 for 18 inch F4 Teeter with LIghtholder mirror (9700 with zambuto)

 

 10975 for 20 inch F4 Teeter with lightholder (11475 for Zambuto)

 

 

in any case these are very nice scopes

 

i'd like to have an 18 or 20 inch scope at some point.  if only there was one that was a one man assemble job (not wheeling on a cart) so that if I felt like handling things on my own at a dark site I'd be good to go



#139 CrazyPanda

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Posted 16 April 2017 - 05:16 PM

very fine looking scope - targeting the premium side of things it seems?  But these are more portable?

 

comparing to some other premium dobs - what are everyone's thoughts on respective value and strengths of these skywatcher stargates?

 

 8640 for 18 inch starstructure GOTO

 

 9600 for 20 inch starstructure GOTO

 

 9100 for 18 inch F4 Teeter with LIghtholder mirror (9700 with zambuto)

 

 10975 for 20 inch F4 Teeter with lightholder (11475 for Zambuto)

 

 

in any case these are very nice scopes

 

i'd like to have an 18 or 20 inch scope at some point.  if only there was one that was a one man assemble job (not wheeling on a cart) so that if I felt like handling things on my own at a dark site I'd be good to go

Once you add the cost of ServoCat ($2700) and required DSC ($600), and the Teeter becomes a lot more expensive.

 

That said, I think the Teeter would be more portable and easier to set up due to the wheelbarrow handles and and quick release upper cage.



#140 Redbetter

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Posted 17 April 2017 - 01:43 AM

Even a traditional 20" f/5 is a one man load/unload and set up (although I don't know if that is true with a driven arrangement.)  That is how I settled on a 20" originally.

 

I will be interested to hear how the mirror holds up in use, particularly the rigors of frequent transport.  I counted the number of curves to my high altitude summer dark site...IIRC it was over 500, one way.  A 2" mirror is pretty tough.  I'm not so sure about this complex thinner mirror structure. 

 

Dew control could be a problem on that secondary.  Dewing of the secondary is a major issue here for 4-6 months of the year and I had to upgrade my dew heater to account for it.  I wonder how a dew heater would be attached on this scope?  A problem with ultra lights like this one is that there is little projection of the UTA, which adds to the dewing and light baffle concerns.  When you start adding weight to the end for a baffle/dew shield extension, counterbalance will be required. 


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#141 wolfli

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Posted 17 April 2017 - 07:19 AM

Even a traditional 20" f/5 is a one man load/unload and set up (although I don't know if that is true with a driven arrangement.)  That is how I settled on a 20" originally.

 

I will be interested to hear how the mirror holds up in use, particularly the rigors of frequent transport.  I counted the number of curves to my high altitude summer dark site...IIRC it was over 500, one way.  A 2" mirror is pretty tough.  I'm not so sure about this complex thinner mirror structure. 

 

Dew control could be a problem on that secondary.  Dewing of the secondary is a major issue here for 4-6 months of the year and I had to upgrade my dew heater to account for it.  I wonder how a dew heater would be attached on this scope?  A problem with ultra lights like this one is that there is little projection of the UTA, which adds to the dewing and light baffle concerns.  When you start adding weight to the end for a baffle/dew shield extension, counterbalance will be required. 

The upper assembly is obviously more exposed than traditional dobs. But it is actually better protected than Obsession UC. The shroud is also made of very thick material that can provide some insulation.

 

Also, it comes with a really nice contourweight kit that should address any balancing problem.


Edited by wolfli, 17 April 2017 - 07:19 AM.


#142 Starman81

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Posted 17 April 2017 - 01:07 PM

very fine looking scope - targeting the premium side of things it seems?  But these are more portable?

 

comparing to some other premium dobs - what are everyone's thoughts on respective value and strengths of these skywatcher stargates?

 

 8640 for 18 inch starstructure GOTO

 

 9600 for 20 inch starstructure GOTO

 

 9100 for 18 inch F4 Teeter with LIghtholder mirror (9700 with zambuto)

 

 10975 for 20 inch F4 Teeter with lightholder (11475 for Zambuto)

 

 

in any case these are very nice scopes

 

i'd like to have an 18 or 20 inch scope at some point.  if only there was one that was a one man assemble job (not wheeling on a cart) so that if I felt like handling things on my own at a dark site I'd be good to go

 

I do believe these StarStructure GoTo prices are for everything but the primary & secondary optics. On the StarStructure Type 3 page, it says 'Customer supplied primary', 'Customer supplied secondary'... So add in $5-$6K for the 18" optics set and ~$10K for the 20" optics (rough Lockwood prices).


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#143 Redbetter

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Posted 17 April 2017 - 02:06 PM

 

Even a traditional 20" f/5 is a one man load/unload and set up (although I don't know if that is true with a driven arrangement.)  That is how I settled on a 20" originally.

 

I will be interested to hear how the mirror holds up in use, particularly the rigors of frequent transport.  I counted the number of curves to my high altitude summer dark site...IIRC it was over 500, one way.  A 2" mirror is pretty tough.  I'm not so sure about this complex thinner mirror structure. 

 

Dew control could be a problem on that secondary.  Dewing of the secondary is a major issue here for 4-6 months of the year and I had to upgrade my dew heater to account for it.  I wonder how a dew heater would be attached on this scope?  A problem with ultra lights like this one is that there is little projection of the UTA, which adds to the dewing and light baffle concerns.  When you start adding weight to the end for a baffle/dew shield extension, counterbalance will be required. 

The upper assembly is obviously more exposed than traditional dobs. But it is actually better protected than Obsession UC. The shroud is also made of very thick material that can provide some insulation.

 

Also, it comes with a really nice contourweight kit that should address any balancing problem.

 

 

The shroud thickness won't have much impact.  What matters is the hemisphere of direct exposure to the night sky--nearly a full hemisphere with the low profile.  That results in a lot of radiative cooling because the effective delta T is very large.  The delta T compared to any shroud surface is going to be two orders of magnitude less, particularly since condensation or frost on the shroud will stabilize its temperature.

 

Counterweighting is not so easy as you imagine, especially on a minimal frame with the back close to the pivot center.  It will likely require a high ratio of counterweight because of the geometry--probably more like a traditional f/5, 5x or something similar.  A Paracorr will be needed adding some more weight.  Put in a 31 Nagler for the widest field and with Paracorr you have ~3 lbs to counterweight, 15 pounds or so?   It is reasonable to assume that a minimal UC scope will be used with the 50mm finder rather than a larger one, and probably a simple RDF, but a simple dew shield out on the end will have to be counterweighted if used.



#144 MSWcdavis

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Posted 17 April 2017 - 08:17 PM

 

very fine looking scope - targeting the premium side of things it seems?  But these are more portable?

 

comparing to some other premium dobs - what are everyone's thoughts on respective value and strengths of these skywatcher stargates?

 

 8640 for 18 inch starstructure GOTO

 

 9600 for 20 inch starstructure GOTO

 

 9100 for 18 inch F4 Teeter with LIghtholder mirror (9700 with zambuto)

 

 10975 for 20 inch F4 Teeter with lightholder (11475 for Zambuto)

 

 

in any case these are very nice scopes

 

i'd like to have an 18 or 20 inch scope at some point.  if only there was one that was a one man assemble job (not wheeling on a cart) so that if I felt like handling things on my own at a dark site I'd be good to go

Once you add the cost of ServoCat ($2700) and required DSC ($600), and the Teeter becomes a lot more expensive.

 

That said, I think the Teeter would be more portable and easier to set up due to the wheelbarrow handles and and quick release upper cage.

 

 

 

 

very fine looking scope - targeting the premium side of things it seems?  But these are more portable?

 

comparing to some other premium dobs - what are everyone's thoughts on respective value and strengths of these skywatcher stargates?

 

 8640 for 18 inch starstructure GOTO

 

 9600 for 20 inch starstructure GOTO

 

 9100 for 18 inch F4 Teeter with LIghtholder mirror (9700 with zambuto)

 

 10975 for 20 inch F4 Teeter with lightholder (11475 for Zambuto)

 

 

in any case these are very nice scopes

 

i'd like to have an 18 or 20 inch scope at some point.  if only there was one that was a one man assemble job (not wheeling on a cart) so that if I felt like handling things on my own at a dark site I'd be good to go

 

I do believe these StarStructure GoTo prices are for everything but the primary & secondary optics. On the StarStructure Type 3 page, it says 'Customer supplied primary', 'Customer supplied secondary'... So add in $5-$6K for the 18" optics set and ~$10K for the 20" optics (rough Lockwood prices).

 

Then thanks to skywatcher for producing these dobs at these prices. 

 

These look beautiful to me. I'd buy one if I could be assured to be able to load it in my sedan and build it myself at a dark site.  (Doubtful I know)


Edited by MSWcdavis, 17 April 2017 - 08:17 PM.


#145 IVM

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Posted 28 April 2017 - 05:22 PM

Even a traditional 20" f/5 is a one man load/unload and set up (although I don't know if that is true with a driven arrangement.)

I assume you mean on even ground, like paved. This Skywatcher looks like something I could use all by my lonesome without ramps - a big deal.



#146 mark379

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Posted 02 May 2017 - 09:30 AM

Very nice for 6 seconds! The real test would be to use an Atik infinity video camera. Then these scope could really shine. In AltAZ, would you be able to track enough to get 30 seconds? Do you use any de-rotator program? If possible then you may be able to triple the aperture at the video screen of this big scopes. Would be a real good way to market these.

Here are some images through the scope. 

 

All are 6 second exposures, ISO3200, Canon 60Da, F/4 Coma Corrector on the 18" Stargate GoTo.



#147 Redbetter

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Posted 08 May 2017 - 01:54 AM

 

Even a traditional 20" f/5 is a one man load/unload and set up (although I don't know if that is true with a driven arrangement.)

I assume you mean on even ground, like paved. This Skywatcher looks like something I could use all by my lonesome without ramps - a big deal.

 

 

Whatever ground I encounter.  Sometimes it is concrete, asphalt, granite, gravel, sometimes grass...sometimes very pockmarked uneven field.  Sometimes it is with an incline (especially my driveway.)  I haven't found a place yet that would be suitable for observing that I could get my 4WD truck to that I couldn't figure out how to load or unload the scope alone. 


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#148 Craziestoozzy

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Posted 25 May 2017 - 12:26 AM

G'day from Australia.

I have some thoughts of my own to share here, with respect to Sky Watcher and their 500p 20" Stargate telescope.
I also hope that Sky Watcher or a representative of same, is available to make qualitative and informed comment.
I have looked far and wide on the internet, for unbiased reviews of this 20" telescope.
Reviews that were performed correctly in a professional and unbiased manner.
Professional as in basic correct testing procedures and unbiased as in free from national (or other) prejudice.
I have used numerous search engines from many countries and have not yet found an informed review anywhere on this planet.
 

With this year's recent N.E.A.P., the consumer got the generic videos and pictures of the outward appearance and physical operation of Sky Watcher's Stargate 500p 20" telescope.
Nothing new there, as several 500p telescope owners from around the globe (U.S.A. and Australia) have already provided such videos.

As an informed consumer, I need more than glossy brochures and advertising hype from Sky Watcher, before I outlay cash.
Before I depart with AU$9000 (for the GOTO version) on a semi-mass produced telescope, I need a guarantee from Sky Watcher that I have purchased a telescope that is not a failure and thus restricted to low magnification wide-field visual use, due to simply being manufactured in bad production run.
On that point, it seems to me that clarification is also needed to match model numbers with production dates for these production telescopes, as there are several different variants in use around the globe, with the most recent productions containing 'minor' fixes.

It would appear that due to the current lack of relevant and precise technical information, that these 500p telescopes are "sold as is," meaning that the buyer assumes the risk that this product may fail to meet expectations or have defects.
 

After my extensive research on the internet, I believe that I am not alone with this concluding thought...
I will not be purchasing one of these 500p Stargate telescopes from Sky Watcher, until I see at least ONE unbiased professional review from an off-the-shelf randomly selected model, that has undergone at least the basics of field and bench tests.


Edited by Craziestoozzy, 25 May 2017 - 12:27 AM.

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#149 Redbetter

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Posted 25 May 2017 - 04:27 AM

Welcome to Cloudy Nights, Craziestoozzy!

 

The difficulty for the manufacturer/vendor is that they obviously cannot do independent reviews of their own equipment.  They have to rely on someone buying the kit and giving it a thorough examination and review, to say what works, what doesn't, and how to make it work for them/you. 

 

While I have some concerns about this or any other lightweight/UC design and particularly the mirror type, I also recognize that there are some major potential benefits assuming it works well.  I agree with you that it is quite a leap of faith to make such an outlay of cash without some critical independent reviews from those who have lived with a production version of the scope for a time.  I am conservative enough that I wait until there is a chorus of people saying, "yep, it's a good scope."

 

When you get to this size range, scopes have their own character, warts and all.  What is ideal for one person might not be for another.  What matters to one does not necessarily matter to others and how they intend to use the scope.  (Viewing height, ladder, bulk, weight, finder arrangement, cooling, DSC's, planetary vs. DSO images, shroud, baffling/focuser shielding from stray light, transportability, durability etc.)  How a scope travels matters greatly to me since I have already made 19 trips to dark sky locations so far in 2017 with over 100 hours of total observing time while there.  Both durability and transportability are critical for me.  Now if I were in the market for a new scope today, and put a new smaller/lighter 20" scope through its paces for my viewing style, and it performed as well as my traditional Dob (probably side-by-side) and was easier/quicker to load/unload/transport/set...I would be effusive with praise.   But in my opinion it takes some time to get to know a scope well enough to pass judgment on it (unless it is really bad.)    


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#150 Craziestoozzy

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Posted 25 May 2017 - 06:48 AM

...it is quite a leap of faith to make such an outlay of cash without some critical independent reviews from those who have lived with a production version of the scope

Cheers mate and thanks for your thoughts and welcome.

As a photographer, I have always sought before outlaying sometimes serious cash on specific gear, reviews from reputable people who are well known as independent in their assessments.
Lens or camera gear comes to mind, with detailed examinations of resolution, CCD or CMOS analysis and a myriad of other aspects that examine all software and hardware of a specific device...all with actual photos taken with the reviewed equipment under certain testing conditions.

A well informed review from a reputable and independent and respected source is critical for Canon, Nikon etc to make successful sales for new equipment.
Additional to the reviews, are the typical word-of-mouth advertising from peers and the first page landing of a Google (just to name one engine) search.

These reviewers are given or loaned the gear to assess from the manufacturer before general public release or at the time of release.
While it is well known that the manufacturer may typically offer their best version of a product for review, there will be little variance of hardware between production runs to create a concern that one may get a 'lemon' that is wildly out of specification.

A review will either confirm or refute a manufacturer's specification claims, give the consumer an informed analysis without the marketing hype and make or break their sales.
While it is all well and good to make a telescope look like it will work and do the job as intended...it is a different story to actually being able to use that telescope in the manner it is designed for.
 

If Sky Watcher want to get up in the world and truly stand out from their competitors, start getting your equipment reviewed before releasing a relatively expensive product as it seems to me that nobody in the astronomy business even bothers to put their money where their mouth is.



 


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