IF Tamron : eBay Guides

Aside from enhancing lens maneuverability, Tamron's Internal Focusing System provides additional benefits to users. Chief among them is a reduced Minimum Focus Distance (M.F.D.) throughout its entire focal length range. Additionally, it improves optical characteristics by minimizing illumination loss at image corners and suppresses aberrations that are caused by focusing positions. Another benefit of Internal Focusing is a stationary focusing ring - regardless of the focusing action. Quick and subtle manual focus adjustments are now a snap. The A014 18-200mm Di-II features an impressive 1:2.7 Macro at
200mm.