Trawlerman, First off, the Sigma 24mm is not even in the same league as the Sigma 16mm FE, even though they share the same filter system. The version of the Filtermatic for the 24mm was an average performer and the Filtermatic feature wasn't offered in their later 24mm wide-angles.
The Sigma 16mm f/2.8 is as good if not better than the Zenitar. Because it has the A-setting on the aperture ring (on my version at least), it is far easier to shoot in every exposure mode.
It is not a very common lens but offers good performance and portability. Obviously because of the crop factor, the fisheye effect isn't as pronounced but it is still a very fun lens to use.
Raybo, if the lens is in good condition and the price is reasonable, I would recommend it. Please make sure that there must be a screw-in filter in place as it is an integral part of the lens construction.
Actual images of the Sigma 16mm FE
The Sigma 16mm f/2.8 Fisheye in Pentax PKA mount
With lens hood (needed for clipping on the 58mm lens cap)
The lens opened revealing screw-in 22.5mm filter
Sample image
Last edited by creampuff; 12-14-2007 at 06:08 PM.