Hold on here...you are talking about a Nikon D3 not being workable because it's to big, and that you need something compact because a big Camera will scare people? And you want o be discreet when you are talking about a 1000mm, and 2000mm
you know those are fucken telescopes and are absolutely FUCKEN huge and make a D3 look like a pea?
You sorta self contradicted yourself. And I don't think I have ever walked through an airport showing off my equipment so I could get targeted...come on dude. It seems like you are just trying to find any excuse here...lol
I don't remember the last time I heard someone referred to ISO as ASA, Zooms can be just as fast as your fixed lens's...my 17-55 is a f.28 my 70-200 is a F2.8 and my 50mm is a f1.4 so I can shoot in any light. My only drawback are my cameras right now. My D70s is a old timer compared to whats out there, my D300 is my salvation right now but still does not posses the low light shooting Awesomeness that is the D3x
I know all about low light shooting...it's the reason I bought faster high end lens's and it's the reason why I want a faster high end camera.
Here is your typical 600mm f4 (which is Nikons Fastest and Longest fixed lens at the moment and cost about 10K) I can only imagine what a 1000m, and 2000m look like
You should post up some pictures of your lens's and of your work...I'm interested in seeing it.