[Peter.M]

I am no expert, but I think for long exposure deep sky photos (what I assume you want to do because your talking about guiding) the mirror will still move. It may not cause a focus shift, but the stars will still move. I would ask though what you want to do with your photos?

Unfortunately the scope you have is probably not suited to DSO imaging. Its focal length is far too long. At these lengths people usually have to use adaptive optics, and need excellent seeing.


EDIT: i just saw you are using faststar ( i dont think you can use an OAG with it)