75mm F/3.9 w/LockIris: ManualMount: C1/3" Angle of View (wide/telephoto) 3.5° x 2.5° 1/2" Angle of View (wide/telephoto) 5.0° x 3.5° 2/3" Angle of View (wide/telephoto) 6.9°x 5.2° Effective Diameter (Front/Rear Lens) Ø18.4mm/Ø10.7mm Minimum Object Distance 19.7 in. (0.5m) Back Focus 27.115mm (in air) Filter Size M25.5 P=0.5 Maximum Diameter ø1.1 in. (ø29mm) Overall Length 2.6 in. (65.5mm) Weight 2.4 oz. (68 grams)