Posted By Thomas Bennett
I've read that binoviewers with smaller prisms can vignette when using long focal length and/or wide field eyepieces. But doesn't this also depend on the scope being used? For example, a F15 Mak-Cass scope will have a narrower light cone 5-6 inches (typical binoviewer position) inside it focal plane whereas a F6.3 SCT will have a wider light cone at that same position. So wouldn't it be possible for the SCT to vignette while the Mak wouldn't using the same binoviewer and eyepieces?