Two large radial fans for fast thermal … 1270mm Focal length f/5. Deluxe Red-dot finder. Explore Scientific FirstLight 10″ Dobsonian 2.5″ HEX focuser with helical gearing Red Dot viewfinder 25mm SPL eyepiece. Explore Scientific FirstLight 254mm f/5 … 2" two-speed focuser with 10:1 speeds. 15% Off: Explore Scientific 10" f/5 Truss Tube Dobsonian Telescope MFR: DOB1045-00. 1270mm Focal length f/5. B&H # EXFLMAK100MC MFR # FL-MC1001400TN. Two large radial fans for fast thermal equilibrium. Primary Mirror Diameter 254mm Focal Length : 1270mm Focal Ratio : f/5 Primary Tube Weight : 36 lbs Rocker Box Weight : 25 lbs Total Weight : 61 lbs. Deluxe Red-dot finder. Buy now & save $170. Explore Scientific FirstLight 100mm f/14 Alt-Az Maksutov-Cassegrain Telescope with Twilight Nano Mount. Key Features. Explore Scientific 10" (254mm) Truss Tube Dobsonian. Aperture: 10" (254mm), Series: Explore Scientific Dobs, Type: Dobsonian Telescopes Lightweight … 2" two-speed focuser with 10:1 speeds. FirstLight … Explore Scientific 10" (254mm) Truss Tube Dobsonian.