Thanks. You guys are a hoot. My go to has always been the 18-200 with my APC bodies. I'm kind of a wide guy and when I shot film, 24 was the norm. On a whim I took the fish-eye on our first cruise (el cheapo manual brand x).
I've always had no issues with the distortion. I most likely will not carry to Alaska since my bag might need other glass. I have found that the 10-24 at 10 does nearly as well and is Nikon glass.
For Alaska it will boil down to how much will fit in the bag. I want something longer than the 18-200 to shoot from glacier and whale tours. I'm not sure it makes sense to carry the full frame body & 28-300 when I might instead carry the 150-600 and two APC bodies. Again one bag.
I had never even considered stitching frames together to get wider. I don't consider myself much of a post processor. So that leaves the 8mm out for sure. I'm a bit worried about having a blank spot if the bag carries 2 APC bodies, 10-24, 150-600. Then I might need to add a 18-70 or the 18-200 to fill in that. Add all the other crap (chargers, batteries, memory cards, SB-400 flash, a filter or two) and the backpack is full.
Astrophotography? We may have crossed paths? Amateur since Jan. '83 and more than a couple of Texas Star Parties, Okie-Tex, & Winter Star Party. Native Houstonian.
Just an update. Got a simple app for the Moto X called Simple GPS. It is just precisely what I was looking for. Was free, gives number of Sat locked, Lat and Long to 7 decimal places, altitude and speed if moving and also a compass. It's very simple, fast and my phone has a hell of a lot more CPU power than the 20 year old Trimble I was thinking of carrying on board.