Depends on how they have been treated.
20x80 sound a little heavy. You will need a tripod probably.
20 being magnification and 80 being aperture, the field of view may be a bit small.
But read this:
http://www.iceinspace.com.au/76-308-0-0-1-0.html
Personally the best binos I know of for wide field astronomical use are the Orion mini giants. 9x63.
Light enough to hand hold (but better with tripod as will any bino).
They are wide field of view and that makes them easy to navigate the night sky. And the image is clear and crisp.
See a recent bino thread discussion in the beginners forum
here
http://www.iceinspace.com.au/forum/s...ad.php?t=56486
and a very comprehensive article is introduced by iceman
here
http://www.iceinspace.com.au/forum/s...ad.php?t=17825
happy reading, cheers