Such lens does exist - and that's the OP's lens (Samyang 12mm fisheye). It has stereographic projection according to lenstip:
http://www.lenstip.com …8_ED_AS_NCS_Fish-eye.html
Thanks ! Didn't know it was a stereographic one.
I'll check the reviews... let's see if the good old Canon 15mm is going to have a new owner 
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UPDATE: I have checked the lenstip review, and it seems the lens is not that great at the edge of the frame.
I wonder if they got a bad copy.
I own its smallest brother (the 8mm f/2.8 for APS-C NEX) which is also stereographic and optically amazing, although a different optical design.
Need more reviews.




