The 70–200mm is one of the most popular telephoto zooms for amateurs and pros alike. Add today’s robust image-stabilization technology, and suddenly f/4 zooms are more than just a budget alternative to f/2.8s. Tokina’s first crack at a stabilized full-frame version comes with a lot of promise. Available for the time being only in a Nikon mount, this new Tokina, at $1,099 (street), costs a full $300 less than Nikon’s original. But is it as good?