FWIW I have the TT Artisan 10mm f2.8 Ffisheye and it is a stellar lens, very sharp across frame already at f2.8. Very high contrast and almost complete lack of flare. Mechanically robust, smooth and excellent. Also, being a 10mm FF lens, this signifies near stereographic projection, which means lens barrel distortion, ie, the center is smaller than it would be with a 16mm FF fisheye, so the distortion is more evenly distributed across the frame, which I find much more pleasing. It puts the older Korean Samyang I have to shame, and is far better than my 15mm f2.8 Fisheye-Nikkor in the corners, as well as having more pleasing projection. Kudos to them!