[66711]71FL F4 Astrograph Set Part # 66711 Description 71FL F4 Astrograph Set Aperture 71mm Fluorite Focal length 280mm F-ratio 4.0 Lens configuration 6 elements in 5 groups Coating Fully multi-coated Physical length 330mm Tube diameter 80mm Weight 1.2kg Filter 72mm (front cap) & 48mm in front of reducer Parts included 2573, 7151, 7801, 7835, 7872 & 7352 Notes 2573 is the 71FL objective assembly without M57 extension tube