As of July 2015, the Pentax HD DA 560mm F5.6 ED AW is the longest prime lens in production under the Pentax brand. It has a telescope-type optical design.Pentax HD DA 560mm f/5.6 ED AW Telephoto Lens Announced, ePHOTOzine The lens is fully compatible with the K-1 full-frame DSLR and covers the 35mm image circle. On the K-1, lens correction profiles are supported to remove chromatic aberrations and vignetting.K-Mount Lens Compatible with 35mm Full-Frame Format, Pentax Roadmap
References
External links
Official product page, Ricoh Imaging Press release, Ricoh Imaging Examples of images list, PENTAX K-1 Laboratory A look at the Pentax 560mm f5.6, YouTube DA 560mm F5.6 ED AW Review, PentaxForums.com DA 560mm F5.6 vs Sigma 500mm F4.5 Review, PentaxForums.com DA 560mm F5.6 - is it a Full-frame lens?, PentaxForums.com