We tend to crop our snaps down lots, compare
and
ISO turned up to 800 allows 2000sec at f5.6, before crop 3888x2592 after 673x449. I know this is extrem but I would rather start with 10m pixels than crop from 6.
We use a canon 400d mostly with the "cheap" 55-200zoom.
And as you can see, we aint too fussy either......