GSO Coma Free 8" F6 Dobsonian for photography

  Basic Manual for Focuser Adjustment & Optical Alignment Coma Free Optics This big GSO Dobsonian reflector features a 8" (203mm) diameter parabolic primary mirror with 94%-96% reflectivity.  Coma is an inherent property of telescopes using parabolic mirrors.  This results in an image that is not in the center of the field looking wedge-shaped. This causes stars to appear to have a cometary coma in traditional Dobsonian reflector. Built in GSO Coma Corrector is optimized by 3 elements fully coated lens, providing pinpoint stars to the edge of the field with no increase in magnification.  We pursue the optical performance beyond everything. We provide the excellent optical performance with affordable price.    The Advantage of Photography There are several brands Dobsonian in market which you can not take a picture directly with.  Because of the short back focus, the focuser is not short enough for direct photography.  They are really designed for observing but not for photography.