William Hamblen writes:

I picked up one of these recently. It looks like a fun toy, with the
emphasis on toy. It's better than those fisheye adapters that screw
onto the front of a lens, but not by much. There's a lot of lateral
color. You need 35 mm film or a full frame digital sensor to get the
full circle. It looks like you do get the whole 180 degrees in a 19
or 20 mm circle. The lens is fixed focus and has a pre-set diaphragm.
None of that automatic stuff. If you never had to work one of these,
there are two aperture rings: one ring with click stops where you set
the f/stop and one ring that you turn to open up the lens for framing the
shot and then turn back to close the diaphragm to the shooting aperture.
It's a throw-back to the'50s, if not the '40s. The depth of field is
so huge that you are in focus from about 2 ft to infinity. Wide open the
lens is f/5.6 and fully stopped down it is f/45 (!).

I don't really understand what sets the circle diameter. I've got a
Pelang 8mm full-circle fisheye that just slightly clips the edge of the
full frame on one side (maybe it's partly a mount centering issue).
That one focuses, so I can get closer than 2 ft, which I find quite
useful with a fisheye. It's also pre-set (not the first pre-set
diaphragm lens I've owned; I'm old :-) ).

I've had surprising amounts of fun with it. The edges are very blurry,
I often end up masking it to a sharp edge (or to a fake rolled edge).

I know what you mean about throw-back -- but I can't find any references
to fisheye lenses existing before 1972 :-)

Note that Sigma makes a 4mm fisheye, for full-circle images on APS-C
sensors.

A couple of shots of mine with the Pelang:

http://dd-b.net/cgi-bin/picpage.pl/photography/gallery/Como-2009?pic=ddb%2020090926%20010-004
http://dd-b.net/cgi-bin/picpage.pl/photography/gallery/fourth-2009?pic=ddb%2020090704%20010-354
--
David Dyer-Bennet, ; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info