My Canon Rebel XT at prime focus on the Meade 285 can resolve a separation of 14.4" (arcseconds), and my camera maxes out around 28" with a 300mm lens.
|Background: 12 frames stacked in DSS, each at 300mm, f/5.6, ISO 1600, 1.3 sec; Callout: Single frame cropped and enlarged in Photoshop|
This was another time-consuming-but-moderately-worth-it preparation layering an enlarged (400%) single frame over a single frame, over a stacked image to try to provide the sharpest view of the double star possible, while providing some context. It's more interesting that just looking at two dots against an all black background, while avoiding star trails at the same time.
I think I'm going to try to do something like this with all my double star photos (if I have time).