A few large telescopes and mounts are excluded from this free shipping offer. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart. International Customers: Free shipping does not apply to international orders. During check-out, you will be presented with several shipping choices and costs. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions.
Found a better shipped price? Please let us know. For years, GSO has made dobsonian telescopes sold under various labels. Users of these scopes know the excellent quality of the optics included, and they have a well-deserved reputation for being the finest mirrors in their price range. GSO's parabolic primary mirrors are perfect for those who want to build their own telescopes or replace mirrors in older ones. The aluminum coating is protected by a silicon oxide SiO2 over-coating.
GSO uses high-volume, state-of-the-art, high quality manufacturing and test lines. This very smooth mirror surface results in excellent optical performance with practically no light scatter. Besides parabolic primaries, we also offer matching GSO secondary elliptical mirrors, mirror cells, and spiders all sold separately.
Most parabolic mirrors will have minor uncoated areas along the edge of the mirror. See photo 2 above for an example.Ritchey actual built the first RCT in It had a inch mirror. Unlike classical Cassegrains, RCTs do not have parabolic primary mirrors, but hyperbolic mirrors.
Both have hyperbolic secondary mirrors. Parallax only made a few RCT, all in the inch size. I ordered the third inch telescope they made. It was superb. Smaller amateur RCT with sizes down to 6-inch mirrors did not hit the market until this decade. The both look pretty much the same — flat black interiors, baffled to improve contrast, identical secondary mirror cells and spiders. The only real difference is the RCT has a much larger secondary mirror, which is required to obtain the faster focal ratio.
The 8-inch optical tube assembly OTA came with a finderscope mounting shoe, one two-inch focuser extension ring, two one-inch focuser extension rings, a two-speed GSO focuser, a Losmandy-style dovetail plate, and a Vixen-style dovetail plate. Because I planned to do a lot of imaging with this telescope, I decided upfront to upgrade to a JMI EV-1 focuser, which I consider one of the top focusers on the market. I also purchased a Technical Innovations Robofocus so I could focus the telescope remotely using my computer.
These two upgrades combined cost almost as much as the OTA! The basic 8-inch RCT comes with a steel tube. Carbon fiber will not expand and contract with temperature changes like steel, so it should maintain focus much better as the temperature drops over the course of the night. Since I was purchasing a motorized focuser than can be programmed to adjust the focus as the temperature dropped, I opted to buy the steel tube version of the RCT.
Different vendors sell the steel tube versions with different color exteriors. The Astro-Tech has a white tube. All carbon fiber versions have black tubes. The mount, focuser and CCD camera are controlled by a laptop computer inside the dome, which I can control remotely. When the weather is nice, I set up a control computer on a picnic table outside the dome. In the winter, I set up a computer in my minivan to stay out of the elements. For imaging, I added a Tele Vue 0.
The uncorrected focal length of the telescope is mm. With this correction it is mm. As seen in Image 2 and 6, I had to use all three of the supplied focuser extension rings to achieve focus with my CCD camera.
GSO 12" f/4 Imaging Newtonian - Truss Tube OTA - 12F4TN
Due to the long optical train between the back of the telescope and the CCD camera, I had to attach a couple of one-pound counter weights to the objective end of the telescope to balance the telescope around the declination axis. Imaging with this telescope has been a pure pleasure.
This is a single shot color camera with a built in guide chip. NGC is part of the famous double star cluster in Perseus. This cluster contains myriad orange and red stars. The image was obtained with only a minute exposure, but I captured stars down to magnitude The star diffraction spikes are a result of the telescopes spider vanes.When thinking about the GSO Eight Cassegrain telescope, its worthwhile to look back to Laurent Cassegrain who was a 17 th century French Roman Catholic priest and is given credit for inventing the telescope design that carries his name.
Cassegrain telescopes use a parabolic primary mirror with a hyperbolic secondary mirror. The secondary mirror directs the light through a hole in the center of the primary mirror where it comes to focus.
With all these variations, the original Cassegrain design is commonly referred to as the classical Cassegrain. While the first telescopes were refractors, the first reflector was made by Isaac Newton and is referred to as a Newtonian. For most of the next century, the largest telescopes made were Newtonians. By the mid-nineteenth century, Cassegrains became the preferred telescope for astronomical research for several reasons.
First, the focus is behind the primary mirror. So astronomers no longer had to climb ladders to get to the eyepiece as was required with large Newtonians. Secondly, the mirror design provided long focal lengths without the need for long optical tube assemblies. Cassegrains were lighter and easier to mount on clock drives. Cassegrains were the main research telescope for more than a century.
Cassegrains have never been available in the amateur telescope market until very recently, when Guan Sheng Optical, out of Taiwan, starting manufacturing 6- 8- and inch classical Cassegrain telescopes. In this article I will review the mid-sized 8-inch Cassegrain.
I have purchased a lot of equipment from Agena in recent years, including a Celestron mount and a whole arsenal of eyepieces.Yz125 spring rates
The company offers fast service, free shipping, great prices, and superb customer service! The telescope arrived within 5 days of placing my order. Image 1 shows the care taken in packaging the telescope.Parco racconigi orari
The telescope was wrapped in plastic inside form fitting Styrofoam all in a double-layered cardboard box. Everything arrived in mint condition. Like all telescopes sold by Agena, the GSO Eight Cassegrain was evaluated physically, mechanically and optically before it was shipped. After it arrived, I performed a star test and found it to be in perfect collimation. The telescope came with a tube cover, a GSO two speed focuser, one 2-inch extension ring, two 1-inch extension rings, two-dovetail plates, and an installed finderscope base.
The extenders are required in various combinations between the back of the telescope and the focuser to achieve the proper distance to focus the telescope with a diagonal or CCD camera.
One of the two installed dovetail plates is the wide Losmandy style, while the other is the narrow Vixen style.
This allows the telescope to be attached to virtually any commercial German equatorial mount! I supplied my own 2-inch diagonal, 8x50mm right angle finderscope, mount and eyepieces.
I just happened to have saved my JMI telescope case that I previously used with an 8-inch Schmidt-Cassegrain telescope that I no longer owned.Navteq traffic data
This mount is more than capable of handling this With the diagonal, eyepiece and finderscope attached, the total payload is near 20 pounds, only half the maximum capacity of the mount. As can be seen in Image 3, the GSO Eight Cassegrain has a beautifully crafted black metal tube, although it can be purchased with a white tube. The finderscope dovetail shoe can be mounted on the right- or left-hand side of the telescope.
The GSO 8-Inch Ritchey–Chrétien Telescope
In this image, I have not installed any of the focuser extension rings. However to achieve focus with the 26mm Tele Vue Nagler eyepiece shown in the image, the 2-inch extension ring was required. For balance along the declination axis, I had to slide the OTA all the way down to the focuser end of the dovetail plate.
Using this OTA with a large, heavy CCD camera might require a counterweight attached to the other end of the dovetail plate.The focuser is the most "visible" part of any telescope with the exception of the optics themselves. You touch the focuser all the time, the focuser is responsible for holding your eyepieces or camera in position and moving them precisely into focus in the first place.
This way ultra-precise focus motion is possible for both visual and particularly photographical applications. The features Smooth Focusing Action The Crayford style focusing control makes achieving precise focus for visual observations and astrophotography a breeze and you will experience very smooth and precisely controlled focuser motion with zero backlash and zero image shift.
High-Quality Construction and Features CNC machined from aluminum and anodized black, this focuser comes with a base plate adapter to attach to reflector telescopes.
The inner drawtube glides on 4 precision bearings and a roller shaft and provides. The inner barrel is baffled and painted a flat black to minimize reflections for maximum contrast. The 2" focuser barrel features a brass compression ring so your eyepieces and other accessories will not be marred by the set-screw.
GSO 12inch RC mirror set (price reduced)
Also included is a 1. Tension Adjustment and Focus-Lock The focuser has two large thumbscrews on the underside. The thumbscrew on the telescope side can be used to lock the focuser, allowing the use of heavy accessories or cameras without fear or slippage or losing focus.
The other thumbscrew on the eyepiece end can be used to adjust the tension of the focuser to achieve a focusing "feel" that you like. At the easiest lightest setting, the focuser moves extremely smoothly. At tighter settings, you can still use heavier accessories without sacrificing much of the smooth focuser action. GSO's rated load capacity for their Crayford focusers is about 3 kgs.
The GSO Dobsonian line is particular model serves a very clear purpose, to offer a large aperture and an excellent image quality at reasonable cost. Set-up is as easy as you can imagine very simple assembly with the rocker box and put it on the ground, insert the telescope tube and put the springs in position and you're ready to go to navigates through the night sky by simply moving the tube up or down, or side to side, by hand.
All GSO dobsonian use optical quality BK7 glass, cooling fans built into the rear cell to decrease cooling times, also all dobs use a roller bearing on the azimuth surface providing dozens of support points for smooth swivel motion. Tube : 46 x 48 x cm3 Stand: 15 x 74 x 74 cm3. This device focuses a lot of light. Looking directly at the SUN through this device can result in partial or complete loss of vision.
The 8 x 50mm finderscope mounts in a quick release bracket that slips into a pre-installed metal mounting shoe nearer the focuser. The bracket has two hand-adjust collimation screws that work in conjunction with a third spring-loaded post in the bracket. This makes collimation faster than the traditional three- or six-screw collimation methods used with conventional finder brackets. Offer Of The Week. Software Downloads. Astronomical Events.
One of the many benefits to becoming a customer of High Point Scientific is that you receive Unlimited Tech Support on all of the products you purchase from us. We understand that many of our products are technical in nature and require support. Rest assured that our team of Telescope and Telescope Accessory experts will be standing by The Ritchey-Chretien was designed for photographic use, and while you can put an eyepiece in the diagonal and use it visually, you will get less than "stellar" results.
It is for this reason that we do not recommend an RC telescope for visual use. If you have any questions or need help choosing a telescope that performs well when used either visually or photographically, please don't hesitate to contact us. Using a true Ritchey-Chretien telescope for astro-imaging has been the dream of many an amateur astronomer, but making that dream come true used to be nearly impossible for all but the most financially blessed of us.Mitti ke bartan online shopping in india
Ritchey-Chretien telescopes do not use any lenses in their design. Instead, they consist of a concave hyperbolic primary and a convex hyperbolic secondary mirror. This design provides superb image correction across the entire field as well as very sharp images on-axis.
Optical testing is done several times throughout the manufacturing process, and then before the optical set is mounted in an OTA, it is tested again and hand-corrected if necessary to bring it up the advertised wave front. Quartz is famous for its super low thermic expansion properties, and you will notice the difference when your telescope is exposed to the cool night air.
The primary is mounted in a fixed mirror cell, eliminating the problem of image shift. The secondary mirror is also created out of the same materials as the primary that is not always the case!
Carbon fiber has an amazing strength to weight ratio, and it cools down like a champ. The inside of the optical tube includes a computer-optimized baffle system to eliminate stray light. Three small fans located at the back of the telescope help it reach ambient temperature in a flash.
The focuser rides on a stainless steel track, or monorail when you rack the focus in or out. This updated design feature keeps the focuser from twisting or bending when you have a camera or imaging set-up riding on it. Customers should communicate directly with the manufacturer regarding details of their warranty, as warranties have a tendency to change without notice. Lets Keep In Touch!
Skip to the end of the images gallery. Skip to the beginning of the images gallery.Shopping cart: 0 products Cash box Your account. Tau Atik. Photo Equipment Baader Baader. Adapter Barr and Stroud Berlebach. Solar DayStar. Solar DDoptics Dew Not. Lechner Electric Leica Binoculars and Spot. Meade Meopta Binoculars and Spo. Teleskop Service offers GSO telescopes in the highest quality range.
Dobsonian telescopes from 8" to 12" ap. Shipping costs.
RC Ritchey Chretien telescopes. Very good beginner telescopes. Extension tubes for RCs. Telescopes with GoTo mount - package. Newtonian and RC mirrorsets.This device focuses a lot of light.
Looking directly at the SUN through this device can result in partial or complete loss of vision. Offer Of The Week. Software Downloads. Astronomical Events. William Optics [ Taiwan ]. For cameras with a small sensor, particularly most CCD cameras, no field flattener is needed. For cameras with a larger sensor we recommend the use of a field flattening lens. A better alternative for astrophotography than a modified SC telescopes. The following items are FREE with the telescope listed above.
Micro Fiber Anti-Static Cleaning cloth. Optics Cleaning Fluid. Desiccant Cap - Refillable desiccant cap to protect fine optics. Without corrector, the usable field has ca.Shimza mix on metro fm download
Most of the CCD cameras are sensitive in this spectral range. The image is absolutely free from chromatic abberations and the resulution is higher than most apochromatic refractors in this price range. The RC has a generous back focus allowing to attach many accessories like off-axis-guiders, filterwheels and much more.
The distance from the 2" connection of the focuser to the focus point is mm.
GSO 12" f/8 Ritchey-Chretien Optical Tube - Truss Tube OTA - 12RCT
To reach the perfect focus position, we suggest an extension rings. The position of the rings is between focuser and tube backside. So you always have a good position of the draw tube. The 3" Monorail focuser is a further development of the Crayford design. The load is not carried by four often underdimensioned ball bearings but on a stainless steel track on the base, thus preventing tilting and bending even under high loads. It is countered by a big knurled screw that centers the inner tube exactly to the rail.
Technical details of the focuser: Travel: ca. But RC telecopes are also well known for their expensive price. Made of low thermal expansion quartz.
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