|
I have the TOAG from Orion that Rick mentioned, and you can shift the prism in/out and side-to-side to find guide stars. But I find that if you have a reasonably sensitive guide camera (I use the ASI120MM) then you'll never be without plenty of options. It can be a bit disconcerting to see the comet-like appearance of the stars (you're picking off light at the edge of the field, so get coma and other edge-related nasties), but as Paul noted, it doesn't affect guiding since it is still fairly straightforward for your guide software to estimate the centroid, even if the FWHM looks terrible!
|