Accessories, adapters, prims, eyepieces, flipmirrorfinders, cameras. TAdaptors Worm gears Byers 15cm Mathis 25cm Hamma lens cleaning accessories. Dobsonian telescope Wikipedia. A Dobsonian telescope on display at Stellafane in the early 1. A Dobsonian telescope is an altazimuth mounted. Newtonian telescope design popularized by John Dobson starting in 1. Acdsee Mac Os X more. Dobsons telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low cost telescope. The design is optimized for observing faint, deep sky objects such as nebulae and galaxies. This type of observation requires a large objective diameter i. Dobsonians are intended to be what is commonly called a light bucket3 operating at low magnification, and therefore the design omits features found in other amateur telescopes such as equatorial tracking. Dobsonians are popular in the amateur telescope making community, where the design was pioneered and continues to evolve. A number of commercial telescope makers also sell telescopes based on this design. The term Dobsonian is currently used for a whole range of large aperture Newtonian reflectors that use some of the basic Dobsonian design characteristics, regardless of the materials from which they are constructed. Origin and designeditIt is hard to classify the Dobsonian Telescope as a single invention. In the field of amateur telescope making most, if not all, of its design features had been used before. John Dobson, credited as having invented this design in 1. Dobsonian mounts. Dobson himself identified the characteristic features of the design as lightweight objective mirrors made of porthole glass, and mountings constructed from plywood, Teflon strips and other low cost materials. Since he built these telescopes as aids in his avocation of instructional sidewalk astronomy, he prefers to call the design a sidewalk telescope. It appears that John Dobson simply combined all these innovations in a design that is focused towards one goal building a very large, inexpensive, easy to use, portable7 telescope for the sole purpose of observing astronomical objects as a way to bring astronomy to the masses. Dobsons design innovationseditDobsons design allows a builder with minimal skill to make an extremely large telescope out of common items. Dobson optimized the design for observation of faint objects such as star clusters, nebulae, and galaxies what Amateur Astronomers call deep sky objects. These dim objects require a large objective mirror able to gather a large amount of light. Because deep sky observing often requires travel to dark locations away from city lights, the design benefits from being more compact, portable, and rugged than standard large Newtonian telescopes. John Dobsons telescopes combined several innovations to meet these criteria, including Thin mirrors Instead of costly Pyrex mirror blanks with the standard 1 6 thickness ratios1 1 cm thick for every 6 cm in diameter so they wont flex and sag out of shape under their own weight, Dobson used mirrors made out of surplus glass ship porthole covers usually with 1 1. Since the telescope design has an alt azimuth mount the mirror only has to be supported in a simple cell with a backing of indooroutdoor carpet to evenly support the weight of the much thinner mirror. Introducing Windows Server 2008 R2 Ebook more. Construction tubes Dobson replaced the traditional aluminum or fiberglass telescope tube with the thick compressed paper tubes used in construction to pour concrete columns. Sonotubes, the leading brand employed by Dobson, are less expensive than commercially available telescope tubes and are available in comparatively large sizes. Lumicon Sky Vector Manual' title='Lumicon Sky Vector Manual' />Public Star Parties are held during the dark of the moon at the Associations observing site at Tierra Del Sol. The schedule for these parties maybe found in the. Jims Mobile, Inc. JMI Telescopes is a world renowned manufacturer of astronomical telescopes and aftermarket accessories for the amateur and professional astronomer. A Dobsonian telescope is an altazimuthmounted Newtonian telescope design popularized by John Dobson starting in 1965 and credited with vastly increasing the size of. Shutan Camera Video has terminated operations as a dealer. Shutan accessories mentioned on this page may or may not be available from other sources. Retrouvez toutes les discothque Marseille et se retrouver dans les plus grandes soires en discothque Marseille. Dobsonian scopes are intended to be transported out to dark sky locations, and Sonotubes are claimed to be more rugged than aluminum or fiberglass tubes which can dent or shatter from impacts. Sonotubes have the added advantage of being thermally stable and non conductive which minimizes unwanted convection currents in the light path caused by handling of the tube assembly. A square mirrorbox Dobson used a plywood box for the tube base and mirror housing. This gave a rigid flat surface to attach the carpet support for the porthole mirrors he was using, and made it easy to attach the altitude bearings. A simple alt azimuth mount Dobson opted for a simple to build and use altazimuth mount. He used a gun carriage type design consisting of a flat platform ground board on which sits a rotating box with semicircular depressions cut in the top for the altitude bearings rocker or rocker box. All parts were made from plywood and other common materials. For the azimuth side to side motion Dobson used a combination of Teflon blocks turning on a flat Formica covered surface. For the altitude up and down motion, Dobson used a large diameter axle closet flange turning on Teflon bearing blocks attached to the altitude cutouts. Dobsons use of Teflon on all bearing surfaces and the large diameter of the bearings created a smooth action with a moderate amount of friction, so that a clamp mechanism is not necessary to prevent unintentional motion of the telescope. Barcode Pro'>Barcode Pro. The design of Dobsonian telescopes has evolved over the years see  Derivative designs, but most commercial or amateur built Dobsonian telescopes follow many or most of the design concepts and features listed above. CharacteristicseditThe Dobsonian design has the following characteristics Altazimuth mount An equatorial telescope mount with clock drive was left out of the design. Equatorial mounts tend to be massive less portable, expensive, complicated, and have the characteristics of putting the eyepiece of Newtonian telescopes in very hard to access positions. Altazimuth mounts cut the size, weight and cost of the total telescope and keep the eyepiece in a relatively easy to access position on the side of the telescope. The altazimuth mount design used in Dobsonian designs also adds to simplicity and portability there is no added mass or need to transport counter weights, drive components, or tripodspedestals. Setting up for hard tube dobs simply involves placing the mount on the ground, and setting the tube on top of it. The weight of the Dobsonian style altazimuth mount is distributed over large simple bearing surfaces so the telescope can move smoothly under finger pressure with minimal backlash. The altazimuth mount does have its own limitations. Un driven altazimuth mounted telescopes need to be nudged every few minutes along both axes to compensate for the rotation of the Earth to keep an object in view as opposed to one axis for un driven equatorial mounts, an exercise that becomes more difficult with higher magnifications. The altazimuth mount does not allow for the use of conventional setting circles to help in aiming the telescope at the coordinates of known objects. They are known for being difficult to point at objects near the zenith, mainly because a large movement of the azimuth axis is needed to move the telescope pointing by even a small amount. Altazimuth mounts are also not well suited for astrophotography. Large objective diameter compared to masscost. Low mass to objective size ratio The Dobsonian designs structure as measured in volume and weight is relatively minimal for any given objective diameter when compared to other designs. Low cost to objective size ratio From a cost perspective, a user typically gets more objective diameter per unit of cost with the Dobsonian design.