Sometimes 14mm isn’t wide enough. Honestly, I don’t need a lens that wide, but with popular cropped-FOV DSLRs like the Rebel XT and Nikon D40, you lose a lot of those precious millimeters so there’s definitely a market for something like this. 5.6mm is insanity though — and as you can see, it covers a lot of real estate. Still, if you’re trying to get the circle effect, you’re putting your subject in the area with the craziest distortion. You can use a (probably expensive) Photoshop filter to flatten the image, and it looks like it’s corrected a little strangely, but it works:
I get the feeling that looks a lot weirder in large format. Anyway, it costs $700, which is a drop in the bucket compared to lots of lenses. It’s F5.6 so I question the optics a little, but I won’t knock it till I’ve tried it. Now go take some big, round pictures!