Nikon 8mm f2.8 AIS Fisheye-Nikkor format_17.5mm The Mamiya M645 is a

The Mamiya M645 is a medium-format SLR that shoots 6x4

or buy specially respooled 620 from

effective for outdoor shooting under most conditions

This tiny lens extends less than an inch past the lensmount and provides a pleasant wide-normal field of view (full-frame equivalent to about 40mm)

Most notable issue: the leatherette has been reglued at some point

Nikon 8mm f2.8 AIS Fisheye-Nikkor format_17.5mm The Mamiya M645 is aThe Nikon 8mm f2. 8 AIS Fisheye Nikkor is probably the lens you picture when someone mentions a fisheye unless you're an ichthyologist. But assuming you're not, this is probably the lens. With a huge, bulging front element and a built in filter turret, this lens is clearly not meant for day to day shooting: it produces a circular image in the middle of the frame, without any attempt to correct distortion. Field of view is 180 degrees, so watch where