The HD Pentax-D FA Macro 100mm f/2.8 ED AW from Pentax incorporates an updated optical design and technology to optimize image resolution and contrast and to deliver clear, high-quality images. It is the first Pentax macro lens to feature an AW (All Weather) dustproof, weather-resistant design for high performance in demanding shooting conditions. It can be used under snowy, misty, or rainy conditions and in harsh environments prone to splashing or spraying water. Boasting a minimum focus working distance of just 5.1", this lightweight lens also incorporates a rounded eight-blade circular diaphragm that produces a natural bokeh effect at aperture f/5.6 or above. The durable silver aluminum lens barrel is designed to complement the color of a camera body. HD Lens Coating This lens features the PENTAX-developed HD coating, a high grade, multi-layer coating that reduces average reflectance in the visible ray spectrum to less than 50 percent when compared to conventional coatings, allowing the user to capture high-contrast images free of flare and ghosting. Camera Body-Based Autofocus The body-based autofocus system offers smooth & quiet performance in conjunction with the FREE (Fixed Rear Element Extension) focusing system. Quick-Shift Focus System The innovative focus system allows the photographer to instantly shift the focus mode from auto to manual by rotating the focus ring after the subject has been captured by the camera's autofocus system. This single-action operation eliminates the need for focus-mode switching during fast-action outdoor shooting. Dust-Proof, Weather-Resistant Construction and Durable Aluminum Barrel With seven special seals to prevent intrusion of water, moisture, and dust, this is the first lens of the "Limited" series to feature the PENTAX-original weather-resistant construction. The durable aluminum alloy barrel and weather-sealing allow this to perform in almost any shooting conditions, including snow, mist, rain, or other harsh environments. Life-Size Magnification This 100mm, short-telephoto macro lens provides life-size magnification and a working distance of 5.1" from the subject to the front of lens or 12" from the subject to the image sensor plane. Full-Frame or APS-C Compatible When used on a film camera or a DSLR with a full-frame image sensor this 100mm lens has a 24.5° angle of view. When used on an ASP-C camera, it is the 35mm equivalent of a 135mm lens with and angle of view of 16°. SP Super Protect Lens Coating PENTAX SP (Super Protect) coating on the front lens element repels dust, water, and grease to keep the lens clean and images sharp. Rounded 8-Blade Diaphragm Blades The rounded eight-blade diaphragm produces gorgeous bokeh effects at the apertures wider than f/5.6 while minimizing streaking effects from point light sources. Optical Design One ED (Extra-low Dispersion) element and two Anomalous Dispersion glass elements deliver clear, high-resolution imagery with edge-to-edge sharpness to compensate for various aberrations and minimize purple fringing.