[codemonkey (Lee)]

Since starting out in astrophotography I've been limited to exposures of <= 30 seconds, so this has never been an issue for me, but I've been wondering... how do you align your mount so precisely for exposures that are 20-30mins long?

I've been drift aligning prior to taking my exposures, and I currently wait no longer than 5 minutes for drift to appear before calling it done. If, however, your exposure length is 20m, 30m or longer, is it as simple as waiting for say double that amount of time for drift to occur? That seems like it would take an absurd amount of time to assess the success of any correction made to alignment, so I'm thinking there must be another way.