Tokina's proprietary AT-X technology has been evolving toward optical perfection for more than 30 years. Since our mission began in 1981 we have made continuous advances. Each new model is a further refinement in a continuing legacy of excellence in design and materials. The current AT-X PRO series continues this evolution of excellence by using the most state-of-the-art technology anywhere. The Tokina difference comes from special material selection and assembly technology that employs micron-u...