I deliberately choose between 1/800s - 1/1250s and never go higher above as this, as I need the tip of the wings to be blurry conveying motion...
-> I've found at shutter speed of 1/2000s or above the birds appear to be frozen in mid-air which is not the effect I'm after. Check all my other bird in flight shots in other folders as well. 1/1000s or there about are my sweet spot! Good luck in your purchase as I don't think ISO is an issue with this camera.
