Super-De-Duper quick question!

A fisheye lens! How cool!

The 15mm in particular. I've heard a lot of people that like it, and I've heard from people that have had other favorites.

I know that you have to take your sensor size into consideration when you calculate the focal length, but does this also apply to the distortion from the fisheye lenses?

Would a fisheye work the same way with the 30D?

Just look at a fisheye shot FF and crop to the center 40%. You'll lose most of the fisheye effect.

Funny you should ask, I was contemplating how it would work out myself...I'm fairly sure Jon is correct.

Tokina is about to release a fisheye lense especially for crop sensors, you may be interested in that, just google for "Tokina Fisheye". It's also a ZOOMING fisheye, which makes it even more unique.

The lense should release sometime in October IIRC.