A truly long-reaching lens designed for Pentax K-mount cameras, the 500mm f/4.5 EX DG APO from Sigma is a super telephoto characterized by its relatively fast maximum aperture and apochromatic optical design. Employing a pair of Extraordinary Low Dispersion glass elements to reduce chromatic aberrations and color fringing, this lens produces notable clarity and color fidelity throughout the aperture range. A Super Multi-Layer Coating has also been applied to realize greater contrast when working in backlit or difficult lighting conditions.