Tokina's constant f/4 full-frame ultra-wide — same as ID 950, possible duplicate listing.
The Tokina AT-X 17-35mm f/4 Pro FX is a budget constant-aperture ultra-wide zoom for full-frame DSLRs covering 17-35mm. The AT-X Pro designation indicates Tokina's professional build tier with one-touch focus clutch mechanism.
Optically good for the price — sharp in the centre with constant f/4 providing consistent exposure throughout. The 82mm filter thread accepts standard screw-on filters at 17mm — a genuine practical advantage over bulbous ultra-wide alternatives.
Available for Canon EF and Nikon F mounts with 82mm filter thread at approximately 600g. No weather sealing despite the Pro designation. Minimum focus distance 28cm. One-touch focus clutch enables instant switching between AF and manual focus.
Available used at budget to mid-range prices. The constant f/4 is practical for landscape photography where stopping down is common practice. The Nikon 18-35mm f/3.5-4.5G is lighter and wider. For budget full-frame ultra-wide landscape shooting with filter capability.