Rokinon 500mm f/6.3 Black Diamond Multi-coated Lens for Pentax [Camera] Aperture: F6.3 Fixed Optical Construction: 7 Elements in 6 Groups Angle of View: 5 Degrees; Minimum Focusing Distance: 2.0m (6.1ft) Filter Size: 95mm Focus Type: Manual; Mount: T-Mount Adapter (Included for Pentax)