This Tokina 17-35mm f/4 is as sharp as Nikon's professional 17-35mm f/2.8 AF-S.
It's not quite as sharp and lacks the VR of Nikon's 16-35mm VR.
This Tokina lens has much less distortion than any other ultrawide zoom, regardless of price. Unlike any other ultrawide zoom, this Tokina's distortion is invisible at almost every setting. Nikon and Canon's best pro ultrawide zooms have double this distortion!
Considering that this Tokina 17-35mm is smaller and lighter than either of the Nikon lenses, and costs half as much, it's easy to recommend it for all full-frame film and digital cameras.
The Tokina 17-35mm f/4 is as sharp as Nikon's professional 17-35mm f/2.8 AF-S that costs more than twice as much.
It's not as sharp as Nikon's 16-35mm VR, but no other SLR zoom lens is, either.
This Tokina is blurrier in the corners of FX at 17mm at f/4, just like Nikon's 17-35mm. Both these lenses get sharper in the corners as stopped down, and are sharp at 17mm throughout most of the image, even at f/4.
At 24mm, this Tokina lens is sharp corner-to-corner on FX even at f/4, which is better than the Nikon 17-35mm.
At 35mm, this Tokina is slightly softer at f/4 throughout the frame, and super-sharp from f/5.6 on.