Apeture vs Sharpness In Astrophotography

[Speed]

I've been meaning to post these since Justin - JKeena - asked his question in the help filees. I've also noticed a few other posts regarding night/astrophotography.

I've been told time and again to stop down the apeture to get sharper photo's. True in terrestrial photography, but not really that applicable in astrophotography. So I ran this experiment, to prove that everything is in focus at f1.4 in astrophotography. All stopping down does is cost you light.

All of these photo's were taken with my N80 on a tripod, Nikkor 50mm f1.4 lens, 30 second exposures, and they were taken consecutively on the same roll of Superia Xtra 400. The only thing that was changed was the apeture. The first shot was taken at f1.4, the second at f2.0, the third at f2.8 and the last one at f4.0. As you can see, the stars didn't get sharper, but they sure got dimmer.

BTW, this is the constellation Cygnus, the Swan. It is also called the Northern Cross. And the Milky Way runs right through it, which is the glow you see at the wider apetures.