Developed as the first model of the PENTAX-D FA 645 lens series, the Pentax smc D FA 645 55mm f/2.8 AL [IF] SDM AW not only features optics optimized for high-quality digital photography to assure exceptional image-description performance, but also provides an image circle covering the image area of existing 645-format film SLR cameras. This unifocal standard lens also comes with a dependable, dust-proof, weather-resistant construction for active outdoor photography.