TS-PHOTON 6" F4 Advanced Newtonian Telescope with Metal Tube The PHOTON Newtonian reflector with 154 mm aperture and the aperture ratio f/4 is a fast travel telescope for astrophotography and visual observing. ♦ Aperture 154 mm (6") - focal length 600 mm - focal ratio F4 ♦ High-quality parabolic primary mirror with enhanced reflectivity for a brighter image. ♦ Large secondary mirror for a well-illuminated image with astro and DSLR cameras. ♦ Precise 2" MONORAIL focuser for more stability than with conventional Crayford focusers. ♦ Adjustable primary and secondary mirror cells made of metal, useful collimation aid on the primary mirror. ♦ With only 530 mm length and approx. 5 kg weight, this is an optimal travel telescope which can even be mounted on good photo tripods. ♦ Focus position ready for the TS GPU Superflat Corrector and the TS 2KORRR 0.73x Reducer / Corrector. ♦ Central mark on the primary mirror for easy collimation ♦ Extensive scope of delivery: 8x50 finder, tube rings, 2" extension tube, adapter to 1.25"