At 10mm, the effect is probably similar to using the Sigma 8mm circular fisheye on a crop sensor. The only difference is, instead of sharp edges, you'll get a blurred one aka vignetting.
I was thinking that around 15-17mm the vignetting would be gone on the 5D2. The bonus would be that I could use the Tokina on the 40D for more fisheye effect than I would see with the Canon 15mm.
Does anybody out there have the 5D2 and Tokina fisheye?? Maybe I should just go with the Canon 15mm....
I don't know that much about the Tokina... but I don't think it will fit on the 5D2... it says for digital only, which usually means 1.6 crop cameras like the 20/30/40/50D series.
