SMC Pentax-F 100-300mm F4.5-5.6 Telephoto Zoom Lens Image Format: Full-frame / 35mm film Max. Aperture: F4.5-5.6 Min Aperture: F32-38 Max. Magnification: 0.25x Weight: 605 g (21.3 oz.) and Diameter x Length:72 x 155 mm (2.8 x 6.1 in)