Tokina 17-35mm f4 Pro FX is an Auto Focus (AF) Wideangle Zoom lens with 35mm FF max sensor coverage. When mounted on a 35mm FF sensor camera, it will give you an FF equivalent focal range of 17 - 35mm. With a max aperture of f4 at 17mm, we can not consider this lens fast on wide end but f4 at 35mm is not too bad for tele end.
Tokina 17-35mm f4 Pro FX is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.