can you really do away with a guide scope if you are imaging with a self guided CCD

[seeker372011]

just a very naive question...can you really do away with a guide scope wif you are using these very expensive CCDs? or is it in practice so hard to find a guide star that in reality you need a guide scope and a remote head (or whatever its called?)

Narayan

[turbo_pascale]

The short answer is YES.
The longer answer is, IT DEPENDS.
If you use narrowband filters, the internal guide chip needs to view through the filter, which limits the available guide stars which are bright enough.
It also depends on the focal length you are working at. If you are operating at long focal lengths, and working with a small chipped guider, you may not have a suitable star to guide on in the FOV. At more widefield FOV, you shouldn't have as many problems.
The remote guide head is useful to put on a guide scope, OR you could put in an off-axis guider in the main imaging train, which will solve the issue of differential flexture betwen the guide scope and the main imaging train, but you would want to get one that you could easily rotate to find suitable guide stars (again, an issue on longer focal length scopes).

Turbo