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Altair Astro GSO 8" F8 Deluxe Ritchey Chretien Astrograph (Carbon Fibre)
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Altair Astro GSO 8" F8 Deluxe Ritchey Chretien Astrograph (Carbon Fibre)
The Altair "Fully Loaded" version of this astrograph includes 2x 3" Losmandy-format plates on top and bottom (for more lateral stability than Vixen-format bars) plus 3x extension tubes to go between the focuser and OTA to adjust spacing. The spacers are compatible with the Starlight Feathertouch focuser adapter.
This is a deluxe, "fully loaded" version of the tried and tested 8" F8 Carbon Fibre Ritchey-Chrétien with the following features:
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A 2" Dual Speed Linear Bearing Focuser included as standard. It will handle a DSLR or CCD camera, and a light weight filter wheel perfectly well, and is adequate in most imaging situations. Note this focuser has the Linear Bearing upgrade, and will outperform most Taiwanese dual speed focusers, both in rigidity and pulling power. It is perfectly adequate for a DSLR/CCD camera and light weight filter wheel.
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Or choose an Optional Genuine 2" Starlight Feather Touch dual speed focuser, in the dropdown menu below (shown in the pictures) which outperforms both the standard focuser with zero backlash, greater rigidity and more lifting power. This is intended for customers with heavier large format CCD cameras, filter wheels and off-axis guiders around 4kg.
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Low weight low expansion Carbon Fibre OTA, weight 7.5kg! (16.4lbs) not only giving more accurate tracking but freeing up your mount capacity for other accessories. The use of a carbon fibre weave composite reduces the weight of the optical tube with no loss of strength or rigidity compared to an aluminium tube. It also doesn't store heat like metal, so convection currents are reduced.
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A Losmandy format dovetail plate and Vixen format bar are included, attached to the top and bottom of the optical tube. (A Vixen bar is not included when we have a temporary special offer as mentioned at the top of the page). .
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You can now use one or more Altair TMS Vixen or Losmandy clamps clamps upside down (depending on the top bar type), to attach the rings to the underside and adjust the ring spacing to fit your guide scope without having to buy an additional dovetail plate. A small guide scope is perfect for this. (Click the image for more views).
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3x Heavy Duty Extension tubes included (2x 25mm & 1x 50mm) fitting between the focuser and the telescope. CNC Machined out of solid billet aluminium, zero flex.
- Low expansion Quartz Mirrors with 99% reflective dielectric coatings giving higher reflectivity than standard aluminium mirrors.
- 8" aperture true hyperboloid Primary & Secondary Mirrors.
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Multiple internal light baffles line the optical tube.
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Fast efficient cool down time compared to a normal SCT due to the open-tube design.
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This telescope is designed with enough backfocus to use an off axis guider, AO unit and filter wheel. Therefore, to create the most rigid imaging train possible, instead of placing extension tubes after the focuser it's best to place them between the focuser and the rear mirror cell. Therefore 1x 50mm and 2x 25mm large diameter extension rings are included for this purpose, which can be placed between the focuser and telescope (with zero flex), for adjusting your backfocus.
- Dimensions: OTA length 455mm Outside diameter 230mm Tube weight is 6.2kgs. The central obstruction diameter is 95mm
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Join the Altair Astro Yahoo Group to find out more about this product from other owners, and share experiences or share technical tips, to get the most from your product. (Opens new window).
Reviews of the 8" RC:
Here's a good article on the review of this 8" RC, by a customer.
Eagle Nebula images by Salvatore Grasso RC8
M81 Galaxy by Salvatore Grasso RC8
M63 Galaxy image Salvatore Grasso RC8
Here's a link to more astro images taken with the 8 GSO RC by Salvatore Grasso.
Advantages of RC Astrographs: This true Ritchey Chretien astrograph is completely optimised for imaging. Consider these points when choosing a dedicated imaging telescope.
- Aperture, price and weight. A pure two-mirror optical system means zero colour aberration and a large aperture with high resolution compared to refractors costing many times more and weighing many times more, to gain the same resolution, whilst using a reasonably priced mount.
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No mirror shift. Because it has a fixed focuser, the primary mirror flop and resultant image shift issues associated with long focal length SCT telescopes with moving mirrors are avoided. There is no need for mirror locks and the additional problems these bring when it comes to focusing. There aren't any complex internal parts to move the mirrors back and forth while attempting to keep them accurately aligned so there's less to move about.
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Repeatable focusing. Another benefit of a high quality external focuser, is that the mirrors don't have to move relative to each other to focus the telescope, and so because everything remains in place, the focal point doesn't change outside the tube, making it easier for you to achieve repeatable, accurate focusing time and time again. That's essential for imaging.
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A better focuser for a great price. Unlike a standard Crayford focuser, the LBF focuser won't flex as much and it can take a higher load such as a DSLR or filter wheel, without slippage or backlash. That's because it has a longer and more precise steel load bearing surface, which is in contact with the focuser tube along more of it's length, rather than being supported by bearings with small contact points - a common issue with other Crayfords. This steel track focuser surface will not wear unevenly like aluminium-only surfaces on other focusers.
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Easier to mount and guide. The optical tube is very light yet very rigid and strong, minimising flex. With a weight 6.2kg this telescope is one of the lightest in this aperture range. It can be carried by a reasonably priced EQ mount like the iOptron iEQ45 45lb capacity mount, along with a guide scope and wide field refractor. Using an EQ6 or CGEM is also possible as long as a very light weight guide scope is used.
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Fastest cool-down time in it's class. Don't spend the whole night waiting for your scope to cool down. Closed tube telescopes with corrector plates such as Maksutovs and SCTs can take so long to cool down that they never reach ambient temperature during the whole night. The RC optical tube is an open design, minimising cool down time compared to SCTs with closed tubes, and three rear cooling fans embedded in the rear mirror cover bring the primary mirror down to ambient temperature as quickly as possible. (a battery pack is included or the fans can be powered by a Kendrick controller).
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Contrast and controlling stray light. The internal knife edge baffles and matte black interior ensure high contrast and minimize the intrusion of stray light, reducing background glare on long exposure images. You will never have to to line the interior of this instrument with "flocking paper" to improve contrast - common practise with other imaging reflectors. Because there is no large corrector plate pointing at the sky, it's very rare for condensation or dew to form on the optics and it almost never occurs. However for unusual and extremely dewy conditions, Kendrick dew control system heaters will fit the secondary mirror.
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Optical performance: The surfaces of the Ritchey-Chrétien primary and secondary mirrors are hyperbolic, and are carefully optimised to reduce coma, an optical aberration which results in flared stars at the edges of the photographic field in other Cassegrain designs. The Ritchey-Chrétien design was previously only available in large scale observatory optics, however, as mirror polishing techniques have advanced, they are finally available to the amateur astro photographer at a reasonable price. Further aberrations like field curvature are removed by the field corrector/flattener, available separately, and useful for large CCD sensors, or DSLR users, and is similar to those offered by other manufacturers charging up to four times the price.
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Price and performance for this aperture at an F8 focal length. For the aperture, resolution, and performance, this scope is simply the best value we have been able to source. We do not know of any other large aperture imaging OTA which can deliver results at this focal length which even comes close. Closed tube telescopes with an F10 focal ratio usually cost about 25-30% more. Not only are you paying less money for a genuine RC telescope designed for imaging from the ground up, but you are getting a faster optical system which places less demand on mount, tracking and CCD camera due to shorter exposure times.
Q: Why should I buy this package with the included Linear Bearing Focuser and CF tube? Basically you get a CF tube scope with better imaging characteristics as well as a better focuser than that offered on lower specified versions of this scope, at a very competitive price. The LBF focuser is perfectly adequate for imaging with a normal DSLR or CCD camera and filter wheel, however if you have a very heavy DSLR with, say an enlarged power pack, a larger filter wheel, an adaptive optics unit, or all three, then we'd recommend the Starlight Feather-touch focuser option.
Q: Why should I buy this package with a Starlight Feather-touch focuser? This is for customers who want a focuser to carry heavy imaging accessories such as AO units and filter wheels. We chose Starlight Instruments because of the superb quality of the focusers they manufacture. By combining this in the package from the outset, the cost of buying an SFT focuser and OTA is reduced by a very significant amount.
Join the Altair Astro Yahoo Group to find out more about this products from other owners, and share experiences or share technical tips, to get the most from your product. (Opens new window). We use a fully insured courier for UK and EU deliveries. You may be relieved to hear we do not use postal services to send optics.
Where to buy:
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For European orders, you can order online here.
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Astronomia (2x shops, London and Surrey)
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IO Astronomy (Hampshire)
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Green Witch (2x shops, Birstal and Cambridge)
- Ian King Imaging (Kent)
- Opticstar (Manchester)
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Widescreen Centre (London)
If product is not in stock, please click the "Notify when in stock" button to be informed when the product is ready to ship in the UK & Europe.
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Customer feedback
Customer Reviews
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Author: keith grice
First I would like to thank Ian for his valuable information on this telescope before my purchase.....I would have prefered to collect it from the shop but because of the distance I chose to have it delivered....great 24 hour service, but I was worried that such a sensitive instrument might not be treated delicateley...My worries were without foundation because this telescope was secured and packed in a box within a box within another box....I wondered if it would need to be collimated, but it was perfect and did not need tweaking......I`ve mounted this telescope on my Meade 12" LX200, against all advice, but the Meade tracks perfectly....all I want now is a clear sky long enough to test the optics.....Many thanks Ian for everything
Please note, only registered and logged-in customers can add a product review.
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