[69710]71FL F4 Astrograph Set Part # 69710 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 1.4 kg Filter 72mm (front cap) & 48mm in front of reducer Parts included 2573, 7101, 7780, 7790, 7835 & 7872 Notes No camera rotator included. More convenient to convert to visual configuration. 2573 is the 71FL objective assembly without M57 extension tube