The high performance DA 200mm ED (IF) lens incorporates an SDM system which creates a smoother, quieter auto focus. Featuring a Quick-shift Focus System, switching from auto focus to manual is instantaneous. Developed specifically for PENTAX digital SLRs, the DA 200mm ED (IF) SDM lens has PENTAX SP coating which protects the exposed lens elements, and a focal length equivalent to 300mm in the 35mm format. Weather and dust resistant, it"s the perfect lens for extreme weather conditions. Specifications Lens Mount: PENTAX KAF2 Focal Length: 200mm (equiv 307mm) Aperture: f/2.8 Min Aperture: f/22 Lens construction: 9 elements in 8 groups Angle of view: 8.1 degrees (w/ Pentax DSLR) Minimum focusing distance: 3.9" (1.2m) Filter Diameter: 77mm Maximum magnification: 0.20x Diaphragm control: Fully Automatic Number of aperture blades: 9 Lens Aperture Ring: n/a Tripod Adapter: n/a Hood: PH-RBK 77mm Objective Cap : O-LC77 Case: S120-160 Max Diameter x Min Length: 3.3 x 5.3? (83 x 134mm) Weight (w/o hood): 29.1 oz (825g) Notes: Supersonic Motor, Quick-shift Focus, SP (Super Protect) Coating, Filter Window