So far, I have been getting really good results with the Nikon AF-S Fisheye NIKKOR 8-15mm f/3.5-4.5E ED Lens mated with a Kenko 1.4X Pro 300 Teleconverter, which essentially turns it into a 11-21mm fisheye zoom on my D500 body. In addition to having the sharpness slightly better than the Tokina 10-17, I am seeing far less CA in the images than what I would typically see when using the 10-17.
Currently I favor using it with the Nauticam 180mm dome port with a 30mm extension ring, as well as my newly acquired Nauticam 140mm dome port with a 50mm Nauticam Extension ring. To get the lens to work with the 1.4X Teleconverter I strangely enough found that I could make one of Nauticam’s Focus gears for the Canon EF 100mm f2.8 Macro lens to work – with a slight amount of manipulation to the plastic insert ring for it.
Here is an image from Cayman Brac shot with the lens zoom out at 11mm, 8mm if you go by the zoom ring marks from behind the Nauticam 180mm dome port with a 30mm extension ring. Exposure values: 1/180 s at f/9.5, ISO 400.