Sky watcher explorer 150p 150mm 6 f750 parabolic newtonian reflector optical tube assembly all sky watcher black diamond newtonian reflectors feature 05mm ultra thin secondary mirror supports to reduce diffraction spikes and light loss and high quality paraboloidal primary mirrors to eliminate spherical aberration the mirrors are parabolised to bring all the light rays to the same focal point to produce sharp contrasty images which are full of detail ideal for planetary and deep sky