Sigma 50-500mm F4.5-6.3 APO DG OS HSM Telephoto Zoom Lens with UV Filter for Pentax K-S1, K-500, K-50, K-30, K5 IIs, K-7 - Walmart.com
Jintu 420mm-800mm Telephoto Lens Camera Lenese + T2 Adapter For Pentax K Mount K3 K5 K7 K20d K-s1 K-50 K5 Ii K-7 K-3 K2 Camera - Camera Lenses - AliExpress