Thank you. When it comes sought information, all Jeffs would do.
Will start watching the Youtube. The widest I have is 24/2 and that would
give me approximately 20sec based on 1/500th rule. As it turns out, the days
we are at Atacama are around full moon (I am bummed) but a week before we will
be on Easter Island and hoping to get lucky there in terms of dark night.