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.[1]
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.[2]