Large 250mm aperture delivers stunning viewing experience Innovative collapsible design that retains collimation 1235x more light-gathering power than the human eye Patented tension control handle allows for precise slewing and maximum stability Parabolic primary mirror with Radiant™ Aluminum Quartz (RAQ™) coating for 94% light reflectivity Heavy-duty rocker box with Teflon™ bearings provide a stable base with smooth motion 2-inch Crayford-style focuser with 1.25-inch adapter allows for use of nearly any eyepiece For decades, the Dobsonian stood as a DIY staple of amateur astronomy, usually constructed with two mirrors, a tube and a base. Often referred to as ‘light buckets’, Dobsonians provide users with the highest possible aperture for their money when compared to telescopes of a similar size, such as Schmidt-Cassegrains or refractors. Developed in the 1970s, the Dobsonian-style telescope is an inexpensive solution for bright, detailed visual observing using a simple design. The name ‘Dobsonian’ comes from the telescope’s inventor, John Dobson, a Vedanta monk who popularized sidewalk astronomy and dedicated his life to astronomy outreach. Dobson was well known for constructing large aperture reflecting telescopes capable of deep sky viewing, using low cost materials. These were often made with found materials, heavy cardboard tubes, recycled porthole glass, and plywood mounts. Dobson, who literally wrote the book on how and why to make amateur telescopes, encouraged other astronomers to assemble their own telescopes and taught workshops on telescope making. The Flextube Dobsonian innovates on that original design, offering users the ability to collapse the optical tube using a proprietary truss-tube system while retaining its collimation. The optical tube uses a parabolic primary mirror, constructed of borosilicate, then polished and coated with our proprietary Radiant™ Aluminum Quartz (RAQ™), producing a remarkable 94% reflectivity. With a 10-inch aperture, the Flextube 250P Dobsonian collects 1235 times more light than the human eye! This simple yet effective design is perfect for visual observation of faint objects, such as nebulae, star clusters, and galaxies. Supporting the Flextube Dobsonian is more than just a simple rocker box. The base uses Teflon™ bearings for smooth, easy Azimuth slewing and a patented tension control handle to lock the telescope in place. Once locked on an object, the telescope can support both 1.25-inch eyepieces as well as the heavier 2-inch eyepieces, allowing you to use virtually any eyepiece on the market. All Flextube Dobsonians come with a slew of accessories, including: two 1.25-inch eyepieces, a 1.25-inch eyepiece adapter, a 2-inch eyepiece adapter, dust caps, and a 8x50 finderscope. At Sky-Watcher, we stay true to the traditional John Dobson design, while offering a fresh look for the 21st century. Although we love computerized telescopes, using a star chart to find objects by hand can be far more fulfilling and will improve your knowledge of the night sky. Unplug your electronic devices, step outside, and become immersed in the wonders of the universe. SKU S11720 UPC 050234117203 Optical Info Optical Design Newtonian Mirror Coatings Radiant Aluminum Quartz (RAQ)™ coatings with 94% reflectivity Glass Type Borosilicate True Aperture (mm) 257 Primary Aperture (mm) 254 F/Ratio 4.7 Focal Length (mm) 1200 Secondary Diameter 64mm Secondary Obstruction (by diameter) 25% Secondary Obstruction by Area 6% Observational Info Dawes Limit 0.46 Rayleigh Limit 0.55 Limiting Mag. 14.5 Minimum Magnification 36 Maximum Magnification 500 Light Gathering (compared to next size down) 57% General Info Focuser 2" Crayford OTA Length (Retract/Ext.) 31.5"/44" OTA Outer Diameter 11.375" OTA Weight (with accessories) 33 Dob Base Weight 26.5 Dob Base Measurements 29.5"x20" Zenith Eyepiece Height 48" Accessories Included Finder 8x50 RACI Included Diagonal No Included Eyepieces 20mm/12.5mm Magnification w/ Included Eyepieces 60x/96x Included Case No Corrector No
