50mm F/2.8Iris: ManualMount: C1/3" Angle of View (wide/telephoto) 5.5° x 4.1° 1/2" Angle of View (wide/telephoto) 7.3° x 5.5° 2/3" Angle of View (wide/telephoto) 10.0°x 7.5° Effective Diameter (Front/Rear Lens) Ø17.5mm/Ø10.8mm Minimum Object Distance 17.3 in. (0.44m) Back Focus 22.10mm (in air) Filter Size M25.5 P=0.5 Maximum Diameter ø1.1 in. (ø29mm) Overall Length 1.5 in. (38.5mm) Weight 1.8 oz. (52 grams)