What do I need to mount a scope to my Astrotrac

[maxwolfie]

I have a very good tripod, the Manfrotto geared head, an Astrotrac, a good ball head, a DSLR and a cheap SkyWatcher SW708 on a cheap alt-az mount (manual)/tripod combo that came with the telescope.

I guess I need to mount the alt-az mount to the astrotrac, but how?

EDIT: I just snapped the 3/8" (I think) bolt that the cheapo Alt-Az head uses to screw onto it's cheapo aluminium tripod, maybe I can kill two birds with one stone here, by buying a new Alt-Az head that will mate properly to the AstroTrac's 3/8" thread AND a 3/8" tripod head thread (which are the same thing).

[MrB]

Basicaly, you need one of these: http://www.astrotrac.com/Default.aspx?p=head
Not cheap I know, but an alt-az head may introduce too much flexure.
Any joint or mounting point etc is a potential point of flexure, reducing the number of moveable parts will only benefit you.

[selste]

Hi Greg,
your scope is not that heavy (around 1.5kg plus eyepiece and prisma) - depends basically on the quality of the geared head and the ballhead if it's possible to mount it on the Astrotrac.
You could screw a dovetail clamp (like this one e.g.: http://www.teleskop-express.de/shop/product_info.php/info/p1536_Starway-Dovetail-Clamp---Vixen---Skywatcher-Level.html onto the ballhead and mount the scope on a suitable dovetail plate (http://www.teleskop-express.de/shop/product_info.php/info/p231_Skywatcher-Dovetail-Plate---Vixen-Style---21cm.html) which makes it easy to balance the scope when You're switching eyepieces or decide to use a prism.

We used a Astrotrac mount during our holidays for imaging with a Canon EOS 450D + Battery Grip + 300mm/f4 lens and 1.4x converter (3.5kg +) on a Manfrotto ballhead without any problems at all.
Cheers,

Steffen