Skywatcher 12 inch Dob

[Jooster]

Hi All,

Been a while since I have been here. I have a 12 inch Bintel dob and unfortunately taking my mirror out to clean the other day I noticed the mirror has pitted badly. At first I thought it was growth, but after a couple of hours of soaking it made no difference. I then checked the mirror under light with a loupe and noticed pits.

My options are to have the mirror resurfaced or buy a new one or buy a complete new telescope. I have a Celestron C8 which is and has been a great scope but I do like the larger aperture that Dobs give. I am considering buying the Skywatcher 12 inch goto scope. Could I ask what is the general consensus of this scope. I was always a purist and star hopped but these days I think I would just like to go out and let the scope do the work for me.

Your comments would be appreciated.

[Allan_L (Allan)]

A great scope, pointing accuracy and tracking are pretty good if you take the time to setup properly. (Things that are not so sensitive with non goto).
Levelling base, picking alignment stars at best relative locations, etc.

Downside for me (my previous scope was 12" SW GoTo) was size and weight, especially of the base, when transporting to dark sky locations.
The base is big and is not designed to be dismantled every time (like the 14 and 16). And with both Alt and Az motor drives in the base, it can be heavy and awkward to lift into the back of a van.

But the scope itself is great.
Collapsible is so much easier to setup than strut.
And I found it held collimation surprisingly well over some of the worst roads in NSW. Requiring just a minor tweak each time in general.

In all I would highly recommend it.

[glend (Glen)]

It doesn't cost much to recoat a mirror. Saintech in Tuncurry NSW does it I believe. At least if you recoat the old mirror you can sell it and defer some of the cost of a new scope if you choose to go that way. If you don't recoat that Bintel scope it is just dead money.

SainTech Ion Beam Systems · (02) 6554 9875, Unit 3, No.4 Dee Cres, Tuncurry NSW 2428.*

It looks like their old website is gone, so give them a ring to make sure they are still in business.

[Jooster]

Thanks for your reply. I live about 30k from Melbourne CBD out near the Dandy ranges and have a great view of the Eastern and Southern sky so I don’t really need to transport it as I have fairly dark sky here ( besides the odd house light). Would anyone know what type of power pack I may need?

[N1 (Mirko)]

Sorry for the slight tangent, but what causes pitting in a mirror?

[Jooster]

I did get in touch with them via email and waiting for a reply. I really think the mirror has to be re ground due to the pitting

[Jooster]

I have no idea. I store the scope covered out on my covered and closed in patio. I am just as mystified as you. At first I thought it was mould but after soaking and using isopropyl it didn’t shift them. I then tried light rubbing but it didn’t shift. It is all over the mirror surface. As I said I looked at the mirror under high magnification and they are definetley pits

[Startrek (Martin)]

How old is the scope ? GSO mirrors are made from BK7 glass and do have a shelf life
Why not give Don at Bintel a call , it might be cheaper to by a new mirror rather than re surfacing ??
I bought a Skywatcher 12” Goto dob last year and I’m really impressed with it. Once levelled and 2 star aligned the Goto and tracking is excellent.I use adjustable furniture feet to level it which is adequate.
Mine is stored in the garage fully extended and locked with a scope cloak over it. I use a Bunnings parcel trolley with a foam packer and adjustable strap to transport it out to my viewing location 8m away on the driveway. I’m only 70kg and nearly 60 years old with previous back trouble and have no issue moving or manoeuvring it.Mine is powered from the garage with an extension lead and plugs into a Powertech 12V 7.5 amp power supply velcro’d to the base. I also have Kendrick dew heaters on the secondary, finder scope and at the eye piece location. As far as optics go I can’t fault it , extremely good although I use premium eye pieces and filters ( Ethos, Delos and Panoptic etc ) Incredible views of galaxies, Nebula , clusters, planets and the moon. I only have 2 criticisms if you could call them criticisms. One is the Skywatcher dual focuser. The barrel assembly is light duty and the thumb screws are cheap and flimsy.The Bintel GSO dual focuser is heavy duty and engineered better with good screws, a nice solid fit for your eye pieces. The second is no adjustable feet to level the base which is strange for a Goto product. I bought a Skywatcher black elastic shroud to fit over the OTA to stop stray glare which is a must if your not at a dark site.
All in all a great scope !!
Good luck

[glend (Glen)]

I would check the secondary as well. Chances are it is simply years of condensation cycles interacting with the orginial coating.
Bintel does sell GSO primaries and secondaries, which are pretty highly regarded but you would need to make sure the focal length matches if using them to replace the Skywatcher mirror.

[Jooster]

Thanks for all you replies. Can I retro fit the GSO focuser from my bintel to the Skywatcher Dob?