High mags and a tiny field of view make for a very dark background fov, and is something you should try in the gathering twilight (esp. w/a 72-inch wow). Also a hood over the head is going to be good for preventing back reflections - anything to increase contrast. There is supposedly an optimal detection mag (and exit pupil) but most scopes are way too low. Search on Mel Bartels or goto: http://members.efn.org/~mbartels/aa/visual.html Which may have been posted here before. Jack > > Except for seeing the very faintest things, astronomical twilight > is more-or-less irrelevant. It is nearly as dark as it's going to get > within 10 minutes of the time of nautical twilight, and for things > such as picking up M30 next Sunday morning, I wouldn't be worried > observing well into the interval between the end of nautical and the > beginning of civil twilight---something like that not-quite-arbitrary > 10-deg figure Tom P used. For ordinary deep-sky observing I'd > certainly start work shortly after nautical in the evening. > /Brian -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.