Thanks for the responses. How do you know the area a particular brush can cover, I want to be able to do things with detail but also cover area easily.
you need to look at the specs for the airbrush your looking at. they'll give them based on the needle it comes with - but you can buy a finer tipped needle or a heavier one for larger spray areas.
for example, my Iwata can go from a hairline to a 2 in spray pattern.