Best Canon Image Stabilised Binoculars for Astro

Hello

I am thinking of getting a set of these to replace by current 9x63's that I
use for casual astronomy and bird watching. When I say casual, I mean
planets, 'bright' deep sky etc. I do use them with a tripod if I am not
travelling. I friend of my as a pair of 12x36's Canon IS that are nice and
light and seem to have a good flat field of focus.

My questions a

1) Anyone using a pair of the bigger 15x or18x50mm's for Astronomy?

2) If so are they a bit heavy for sustained 'hand' use?

Obviously they won't have the light grasp of my current pair and the exit
pupil is small but on the face of it not having to us a tripod and the flat
field the IS bit is a big plus for the Canons.

Thanks for reading.

Neil Miller
Surrey, UK