I intend to capture the ISS in video. I could track it before, keeping it in sight for a few seconds here and there, but I don't know which exposition time I should use for the camera, and I suspect it will be hard to discover and adjust it in real time.

Do you have any suggestions? I have a SCT 8", and I plan to use a f/3.3 reducer and a DMK 21AU618.AS in prime focus.