Sky-Watcher 20" Stargate 500P Dobsonian - Page 2

Shiraz (Ray) · #21 01-03-2017, 01:12 AM

good point - a top quality mirror would be of no value with some older eyes. Might be an additional factor that the OP could consider.

CraziestOzzy · #22 07-03-2017, 02:35 PM

Thanks for the replies people.
I have looked far and wide for some optical tests on the 20" mirror, didn't find anything as yet.
Figuring Stargate 20" is still a 'new' mirror.
I did find this video (not in English), that covers the earlier 18" version and if you are hard for time, go to 9:45 of the video to view the good stuff.

Video HERE.

Seeing conditions up here (Townsville) are not that great for at least half of the year, when the humidity is high and upper wind shear strongest.
I do have close access to a mountain that is just shy of a 1000m above sea level and will be using this location a lot during the Winter for visual observing.

Reasoning for seeking a large aperture for visual observing, is to grab as much light as possible for viewing through a low magnification and wide field eye-piece.
The down side with this approach, is that high magnification eye-pieces will be next to useless if the atmospheric conditions are not ideal.
Which is why I will settle for low magnification and wide field viewing with the option of high magnification if the atmospheric conditions are right.

Also, having dabbled over the years with astronomy, I roughly know what I want (cough) and want to get my first ever big purchase right the first time, without spending extra money on future bigger aperture scopes.

I have starting looking around Brisbane area for the availability of the 20" and asking questions (nicely

) and talking shop.
Seems the scopes are very limited in supply in Oz, so might have to wait a bit for one to be available.

Having said all that, thanks for your help...and when I do get my hands on one of these beasts, I will for sure place an unbiased and technical review of this scope...which is sorely lacking at the moment

dannat (Daniel) · #23 07-03-2017, 03:27 PM

pretty sure MAtt from telescopes-astronomy has an 18" demo model 4 sale if you're interested

gaseous (Patrick) · #24 07-03-2017, 07:11 PM

Have you seen the process involved in setting up the 18" or 20 Skywatcher? There's a YouTube video showing a chap (from Australia and on IIS I believe), setting one up, and the thought of going through that process in the dark every time gave me chills. Perhaps I'm a Luddite, but it seemed more hassle than a supposedly peaceful and relaxing hobby should warrant.

CraziestOzzy · #25 07-03-2017, 08:36 PM

Yeah mate, seen all available vids from Russian, Greek through to English.
Even had a look at the ones where they actually unpack the gear on delivery.
Fairly amazing in my view, is the ease of transport and setting up for each session.
Just crazy looking at the boxes that come shipped on delivery.
I would bet that there will be a few dry runs in the home, to have setting up down pat and would prefer setting up on location during daylight

Great chance for Zen moments while setting up, with promise of a brew at the end of it...but that's me.

Troy · #26 11-03-2017, 05:40 PM

Quote:

Originally Posted by dannat

pretty sure MAtt from telescopes-astronomy has an 18" demo model 4 sale if you're interested

That's one hard site to navigate where is the 18" demo?

dannat (Daniel) · #27 11-03-2017, 05:50 PM

it was on his newsletter, check the last one he sent out, also he had a skywatcher clearance sale list

CraziestOzzy · #28 21-04-2017, 02:17 PM

With the end to the 2017 NEAP, a post over on Cloudy Nights forums was revived.

LINK here

Some incite into the quality of the mirror, with mixed thoughts providing a balanced opinion to both sides of good and bad.
One thing for me to keep an eye out on with any future reviews that may hopefully surface, is the astigmatism from either primary or secondary due to the way they are both mounted to hard surface.
I believe that the design of the primary (while nothing new there), is sound as is also the mounting of the primary...but time will hopefully reveal some qualitative reviews.

A quirk I have noticed and one to make sure of...is to ensure that the telescope to be purchased is in fact a new model with the most recent hardware enhancements and corrections.
Seems to be some earlier production runs out there.

gaseous (Patrick) · #29 21-04-2017, 03:43 PM

It's amazing that these have been around for 18 months or so but there are very few (that I've found) reviews on the mirror/observing quality. A lot of conjecture due to the assembly method, a lot of detrimental comparisons to prestige mirror makers (?) but no real reviews by expert observers.

CraziestOzzy · #30 21-04-2017, 04:37 PM

Quote:

Originally Posted by gaseous

It's amazing that these have been around for 18 months or so but there are very few (that I've found) reviews on the mirror/observing quality. A lot of conjecture due to the assembly method, a lot of detrimental comparisons to prestige mirror makers (?) but no real reviews by expert observers.

Yeah, totally agree with you mate on all points.
I am hoping that with exposure (and recent availability) to the USA consumer, such voids will be filled shortly and watching the WWW closely.
Half way to saving the pennies on this 'scope, but will await for some unbiased reviews and actual real world testing, before I part with 10 grand.
Some reviews from the Netherlands and France...but they both bogged down with the usual Western bias against cheap Chinese manufacturing.

One thing is for certain should I ever buy this 'scope...I am going to ditch that flimsy thin plastic mirror protector and replace with a sturdier cover.
Having watched a few videos on the assembly of this 'scope, the supplied plastic cover will not seat and lock firmly and protect the primary against secondary dropping onto it or the truss tubes accidentally knocking against the side or face of the mirror.
One video actually shows large chunks of broken plastic on the sides of the mirror cover...so it is a safe bet the truss tubes will knock the mirror sides during assembly and require a more solid mirror protector.

sn1987a (Barry) · #31 21-04-2017, 10:09 PM

5 people who want one get together chip in 2k each, do a review and put everyone else on iis out of their misery. That way if its a POS you've only blown 20% of your money and you'll live to fight another day.

Rickster (Rick) · #32 03-07-2017, 10:15 AM

Hi all,
I just purchased one of these babies and will pick up this week.
I'll give you a summary after I give it a decent shakedown.

Rick

gaseous (Patrick) · #33 03-07-2017, 10:20 AM

Good man! Can't wait to hear your thoughts.

electric · #34 05-07-2017, 10:29 PM

Hi everyone!

My first post!

At the South Pacific Star Party, Serge from Astro Devices had his Skywatcher 18" dob set up next to Alex's 17.5" from Gondwana Telescopes. I got to use both scopes. BIG difference between the two.

Both sets of optics were really nice. The difference was the structures. The action of Alex's dob was silky smooth, needing just gentle effort to move. So nice to use.

Serge's dob is a backlash monster, so stiff and difficult to move, and it bounces!. It was impossible to manually track at high magnification. A real disappointment for all its flash appearance. With all the talk about these dobs from Skywatcher you would have thought the build quality would be up to scratch. But you get what you pay for, don't you.

Steffen · #35 06-07-2017, 01:56 AM

Alex, being an experienced dob user himself, pays extraordinary attention to the usability of his scopes. I don't think any mass-produced-to-a-price-point scope can ever match that.

That said, the bearing mechanics seem to have been the Achilles heel of SkyWatcher dobs all along, ultra-light or traditional. They just don't feel nice. The similarly priced GSO dobs in comparison are buttery smooth and easy to use, even though their optics aren't as highly regarded as SkyWatcher's.

Rickster (Rick) · #36 11-07-2017, 04:38 PM

Hi All,

Just a quick update on my 20” Stargate goto that I constructed last weekend.
At this stage I have set it up inside to check operation and familiarize myself with this beast.
My first impressions of construction, quality etc are all 100% positive.
Contrary to some of the 2nd party negative comments about smoothness of operation etc, I haven’t experienced these issues.
Once the scope was balanced, I did need to add weight to do this correctly and I also use a binoviewer which is quite heavy, the manual operation was fine. Not sure why others may have experienced problems with this? If I had problems as described in previous posts below, I’d be taking it back for a refund!
I also put the light shroud on which I did easily on my own. I’ve heard a few comments about issues with this but I didn’t experience any.
Once manual operation was correct, I then engaged the goto drive motors and ran it through its paces. Very smooth and very impressive.
So in summary, more than happy with my purchase!
Next step is to point it at the heavens.
Cheers
Rick

gaseous (Patrick) · #37 11-07-2017, 04:48 PM

Good to hear Rick! Now that you've done it a few times, what's the average time to set it up? Looking forward to your first light report.

electric · #38 11-07-2017, 06:33 PM

Rick, great to read your experience is a good one.

If you are referring to my post, my experience was not with the goto model, but the push-to.

At SPSP, Skywatcher had a 20" goto. Obviously not your scope as it sat unattended and unused on the Saturday night, laid up with major mirror issues. I am surprised that this has not been brought up at all here. The Skywatcher flagship scope sits idle, much like the Australian Navy's flagship...

I sincerely hope your mirror is a good one

No one drops this amount of money for anything but a good experience

AstroJunk (Jonathan) · #39 12-07-2017, 12:23 AM

Quote:

Originally Posted by glend

The 'Seeing' conditions in your location are going to limit you far more than any marginal gains from a specialty, high priced mirror.

But in the few nights in any decade when the seeing is perfect, I know what quality telescope mirror I want to be using and I say this from experience. To have the view of a lifetime, you have to have a mirror that is figured to perfection and anything less is settling for a lifetime of mediocrity.

BTW I have seen through a number of truly fabulous Skywatcher mirrors, but have yet to use a big un. I expect that they are pretty good though, and look forward to getting some eyepiece time with one

Rickster (Rick) · #40 12-07-2017, 09:34 AM

Quote:

Originally Posted by gaseous

Good to hear Rick! Now that you've done it a few times, what's the average time to set it up? Looking forward to your first light report.

Hi gaseous,

I'd say once familiar with the setup, it should take an average of 20 mins to complete and be ready for viewing. Less if you leave the mirror cradle on the base.
I did this on my own, but would be easier with two people. The base and mirror cradle are quite heavy.

Cheers