Two options, and as you have the C11 i would suggest going with option 1;
Option 1:
- Off-axis Guider (OAG). There are many different types. The Starlight Xpress is rather cheap, around $300. Australian distributor for SX gear is here: http://members.ozemail.com.au/~aeccl...ght_xpress.htm
- Guide camera (Starlight Xpress Lodestar, QHY5 etc)
- Cable to connect camera to mount (unless guiding through software). This is normally included with the camera.
- Adapters to fit the OAG to your camera (varies depending on other adapters and items you have)
- Software to perform guiding. PHD is free and used a fair bit: http://www.stark-labs.com/phdguiding.html
Option 2:
- Guide scope. Most common is a small refractor or finderscope. Something like this is a good starter: http://www.bintel.com.au/Astrophotog...oductview.aspx
- Guide camera (Starlight Xpress Lodestar, QHY5 etc)
- Cable to connect camera to mount (unless guiding through software). This is normally included with the camera.
- Adapters (1.25" extension tube). The guide scope package listed above includes an extension tube.
- Mounting adapters. The package above includes a vixen bar and rings to hold the guidescope, but you need some way to attach it to your scope.
- Software to perform guiding. PHD is free and used a fair bit: http://www.stark-labs.com/phdguiding.html
I mentioned before that Option 1 is better for you. This is because with Option 2 there is a chance that you will get flexure between your C11 and the guide scope which will result in poor images (star trails or fuzzy images). The OAG does not suffer flexure, nor mirror slop.