He says the 300 f/2.8 does better, but I didnt see if he meant wide open or at the same f/number.


I wouldn't have expected the 200mm to do well wide open.


For astro, I think it makes sense to compare images of the same angular size, or the shorter lens has an advantage (though that isn't how we usually compare lenses... looking at iso crops the usual way, the 200mm looks ever so slightly sharper to me)


Anyhow, the 200mm gets pretty much the same sharpness at f/2 as the 300mm does at f/2.8. I know this wasn't what the op's question was about, but I find the 200 to be the more impressive lens for this reason.