So.....am I the only one who wishes someone would make an UWA Zoom with IS?
I think it would be great for handheld shots indoors. When I shoot UWA I nearly always want larger DOF which is why even though I often think of upgrading to the 16-35 I never actually do it.
Personally I would either be shooting fast enough to hand hold the shot, or I'd use a tripod for longer exposures... You've got masses of DoF on an UWA anyway so you shouldn't lose out too much by knocking it back a stop or two when a tripod isn't available.

