I tested it at f/2.8 and f/3.5, mostly.ISO 100. Fixed shutter speed. Test subject relatively close (butfarther than the minimum focusing distance). Upon receiving my refurbished Canon10-22mm f/3.5-4.5, I did the same tests and got superb results (thekind of results I was hoping to see with the Tokina). I'm very happy with the Canon lens.