Telephoto lens series walimex pro lens mount pentax k lens speed 8 focal length 500 mm suitable for sensor type aps c construction prime lens area of use travel photography landscape photography animal photography focus manual focus auto focus af motor no internal af motor max magnification 13 closest focusing distance 170 cm lens type aspherical lens construction groupselements 67 max aperture 8 lens switch afmf filter thread 30 mm co