You could always try the partial frame 8mm Peleng fisheye. Although it doesn't cover the whole 24x36 frame, I've read that it does cover an APS-sized sensor. It's available from some of the Zenitar sources.
Tim On 2/16/05 16:12, frank theriault wrote: > It's an addiction, really. When I got my 24-48mm zoom, I thought, > man, who needs anything wider than this? Then I bought Chang-Sang's > Vivitar 3.8 19mm, and thought, no way will I ever go any wider! Last > month I got the Zenitar 16mm fisheye, and I'm wondering how much wider > I can go. <vbg>

