This is a model built to professional specifications and is based on the AT-X 828AF optical system. Tokina has utilized coating changes in the optical

This is a model built to professional specifications and is based on the AT-X 828AF optical system. Tokina has utilized coating changes in the optical system and the unique floating element system separately focuses the first three and last two elements in the forward lens groups. This provides uniformly high image quality from infinity to close focus. The new exterior finish improves overall handling and durability. A focus clutch mechanism further assures top performance during auto and manual focusing.