The Nikon 10,5 is one of the sharpest fisheye lens in the market, and much sharper then the Tokina 10-17. Many full frame photographers had to stop using the Tokina in high resolution cameras like the Nikon D800 (I know it's a FX lens, but you can use it for circular photos at 10 mm).
Being a fixed lens and a faster then the Tokina (f2.8 vs 3.5-4.5) it's hard to believe that it focus slower.
Depth of field of both wide open, will of course be slightly less in the 10,5 since you'll be using f2.8 vs 3.5 in the Tokina.
- bobanderson likes this