More Info
As any prolific astrophotographer will tell you, the more light you can gather, the better your astrophotos will turn out. Combine light-gathering prowess with a compact design and an affordable price, and you're likely to end up with our new 8" f/8 Ritchey-Chretien Astrograph. As a leading supplier of affordable imaging equipment and solutions for amateur astronomers, Orion is proud to introduce this highly regarded telescope design used by advanced astrophotographers and professional observatories worldwide — and even by the Hubble Space Telescope!
Previously available only in larger apertures that cost thousands more, the outstanding optical design of the Orion 8" Ritchey-Chretien Astrograph will allow you to capture spectacular, detailed images of deep-sky objects like never before. In contrast to conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to coma away from the center of the field, the Ritchey-Chretien utilizes hyperbolic primary and secondary mirrors to achieve wonderfully flat images that are virtually coma-free. In our 8" model, the mirrors are made of BK-7 optical glass with enhanced aluminum 94% - 96% reflectivity coatings, to provide diffraction-limited performance. Since there are no lenses involved, images are also free from chromatic aberration, which affects all but the finest, most expensive apochromatic refractors.
The Orion 8" Ritchey-Chretien Astrograph Telescope is ideal for use with small CCD-chip cameras such as our award-winning StarShoot line, as well as medium-format CCD and DSLR cameras, for deep-sky and solar system astrophotography. The telescope's wide, fully illuminated flat field produces pinpoint star clarity all the way to the edge of the camera's sensor.
The Orion 8" Ritchey-Chretien Astrograph features a machined, dual-speed (10:1) linear-bearing Crayford-style focuser with an engraved millimeter scale on the drawtube. The robust focuser provides precise fine focus adjustment without slippage or flexure with heavy accessories attached. One 2-inch and two 1-inch extension rings are included for adjusting the focus position for various cameras. Focus travel readily accommodates popular imaging accessories.
Orion Ritchey-Chretien Astrographs have been designed with collimation in mind. With an optical instrument of this caliber, precise optical alignment is of paramount importance. Each Orion RC secondary mirror is precisely center-marked to facilitate collimation and we even include a Cheshire collimation tool to make proper alignment of optics as convenient as possible.
The 21-inch enameled steel optical tube weighs only 15.8 lbs. and features a dovetail mounting bar underneath, for trouble-free setup on medium or large-sized Orion equatorial mounts. The inside of the optical tube is fortified with ten computer-positioned light baffles, and the primary mirror baffle tube and secondary mirror light shield are also highly baffled to ensure maximum image contrast.
Without a doubt, our 8" Ritchey-Chretien Astrograph brings advanced astrophotography performance into the realm of affordability for most amateur astronomers. More affordable than comparably sized apochromatic refractors and without the coma that afflicts Newtonian reflectors, the Orion 8" f/8 Ritchey-Chretien Astrograph Telescope will take your astrophotography to new heights!
Warranty
Limited Warranty against defects in materials or workmanship for one year from date of purchase. This warranty is for the benefit of the original retail purchaser only. For complete warranty details contact us at 800-676-1343.
Warning
Please note this product was not designed or intended by the manufacturer for use by a child 12 years of age or younger.
Product Support
Visit our product support section for instruction manuals and more
Specs
Best for viewing
Brighter deep sky
Best for imaging
Deep sky
User level
Beginner - Telescopes suited for beginners are easy to use and maintain. Very good optical and mechanical quality. A great first telescope that will show you the moon and planets.Intermediate -Telescopes for the intermediate user are more robust in features and performance. Excellent quality in optics and mechanics, and more complex in use. An intermediate telescope will allow an enthusiast to "grow" in the hobby.
Advanced - Advanced telescopes are high performance, with exceptional quality. They may require more commitment to use in set-up time and technical savvy. Some advanced telescopes are easy-to-use but large and heavy. An advanced telescope is a purchase for a lifetime.
Expert - Expert telescopes offer uncompromising optical and mechanical quality for the most demanding amateur astronomer. They may be technically involved or designed for specialized use, such as astrophotography or detailed deep sky observation. They carry a premium price; but are designed to provide the ultimate performance in the field.
Advanced
Optical design
A small, quality achromatic refractor of 60mm to 80mm aperture makes a fine starter scope for observing the Moon and major planets. They're affordable ($100 to $350), portable, and maintenance-free, all desirable factors if you're just "testing the waters" of Astronomy. If nebulas and galaxies are your main interest, a Newtonian reflector or Schmidt-Cassegrain is the way to go. Moving up to a 90mm or 100mm refractor will snare more objects and provide better performance, for a higher price. Renowned for crisp, sharp images, refractors are the priciest per inch of aperture of all telescope types. A refractor is the scope of choice if you will be doing most of your stargazing from city or suburbs, where the night skies are moderately light-polluted. Since viewing is restricted mostly to the Moon and planets a big scope would only amplify the skyglow, yielding poor washed out images. Reflectors Newtonian reflectors are great all-around scopes, offering generous apertures at affordable prices. They excel for both planetary and deep-sky viewing. Of course, the larger the aperture, the more you'll see. Smaller, 3" and 4.5" equatorially mounted Newtonians will provide a nice "survey" of celestial luminaries, and they maintain their portability. Six-inch and 8" Newts have enough aperture to deliver captivating images of fainter star-clusters, galaxies, and nebulas-especially in a reasonably dark sky. Although the 6" to 8" Newts are bulkier and weigh more, with a Dobsonian mount they are easily manageable by one person making them a wonderful beginner scopes. Dobsonian-mounted reflectors have lower price tags than their equatorial counterparts, starting in the mid-$300s for a 6" Dob. Schmidt-Cassegrains If portability is important to you, you might want to consider a "catadioptric" scope such as a Schmidt-Cassegrain or Maksutov-Cassegrain. They pack a hefty aperture into a very compact tube. An 8" Schmidt-Cassegrain provides excellent views of the Moon, planets, and deep-sky objects, and is well suited for astrophotography. Schmidt-Cassegrains should be considered as an investment priced over $1000 for the most basic 8" models (and hundreds more to outfit it for astrophotography). The Bottom Line Now that you've received the crash course on telescopes, here's some parting advice for aspiring astronomers: Get as much aperture as you can reasonably handle. Big aperture is desirable, however you don't want to end up with a scope that is too big or complicated to conveniently set up, haul around-and use! Also, avoid those gee-whiz, techno-toy scopes with the hefty price tags that are showing up in the big chain stores. For a first telescope, we recommend a basic refractor of 90mm aperture or smaller, or a Newtonian reflector of 6" aperture or less, unless you're really committed. After you've learned the basics of observing and developed an appreciation for the hobby, then you can move up to a bigger, fancier scope.
Ritchey-Chretien
Optical diameter
The optical diameter (also known as aperture), is the size of the telescope's main light collecting lens or mirror, measured in millimeters or inches. As the diameter increases, more light is collected and the resolution increases.
200mm
Focal length
The focal ratio of an optical system is the ratio of a telescope's focal length to its aperture. Short focal ratios (f/5, f/4.5) produce wide fields of view and small image scales, while long focal lengths produce narrower fields of views and larger image scales.
1600mm
Focal ratio
The focal ratio of an optical system is the ratio of a telescope's focal length to its aperture. Short focal ratios (f/5, f/4.5) produce wide fields of view and small image scales, while long focal lengths produce narrower fields of views and larger image scales.
f/8.0
Optics type
Newtonian reflectors will have either a spherical shaped mirror, which is less expensive to produce, or a higher quality parabola, which does not result in spherical aberration. Cassegrain telescopes routinely use spheres in addition to other lenses in the optical path to correct for residual spherical aberration.
Refractors use a series of lenses to provide a clear image. Designs range from a standard air-spaced doublet (two lenses in a row) to exotic designs such as oil-spaced triplets and 4-element multi group lenses.
Hyperbolic
Resolving power
The theoretical resolving power of a telescope can be calculated with the following formula: Resolving power (in arc seconds) = 4.56 divided by aperture of telescope (in inches). In metric units, this is: Resolving power (in arc seconds) = 116 divided by aperture of telescope (in millimeters). Note that the formula is independent of the telescope type or model, and is based only upon the aperture of the telescope. So the larger the telescope's aperture, the more it is capable of resolving. This is important to keep in mind when observing astronomical objects which require high resolution for best viewing, such as planets and double stars. However, it is usually atmospheric seeing conditions (not the telescope) which limits the actual resolving power on a given night; rarely is resolution less than one arc-second possible from even the best viewing locations on Earth.
0.58arc*sec
Lowest useful magnification
Lowest useful magnification is the power at which the exit pupil becomes 7mm in diameter. Powers below this can still be reached with the telescope to give wider fields of view, but the image no longer becomes brighter at a lower power. This is due to the fact that the exit pupil of the telescope (the beam of light exiting the eyepiece) is now larger than the average person's dark adapted pupil, and no more light can fit into the eye.
29x
Highest useful magnification
The highest practical limit is different from the often used "highest theoretical magnification" specification. The "theoretical" limit generally is 50x the aperture of the scope in inches (2x the aperture in mm). So for example, an 80mm refractor is capable of 160x, and a 10" telescope is theoretically capable of 500x magnification.
But after approximately 300x, theory breaks down and real world problems take over. The atmosphere above us is constantly in motion, and it will distort the image seen through the telescope. This effect may not be noticeable at lower powers, but at higher powers the atmosphere will dramatically blur the object, reducing the quality of the image. On a good night (a night where the air above is steady and the stars aren't twinkling), the practical upper limit of a large telescope is 300x, even thought the theoretical limit may be much higher. This doesn't mean the scope will never be able to reach those higher "theoretical" powers - there will be that rare night where the atmosphere is perfectly still and the scope can be pushed past it's practical limit, but those nights will be few and far between.
300x
Highest theoretical magnification
400x
Optical quality
"Diffraction Limited" means that the limits of image detail are determined by the physical properties of light, and not by optical defects in the telescope.
Diffraction limited
Focuser
2" dual-speed linear bearing Crayford
Secondary mirror obstruction
97mm
Secondary mirror obstruction by diameter
48%
Secondary mirror obstruction by area
23%
Mount type
Optical Tube without Mount
Astro-imaging capability
The astro-photographic capability of the telescope is based on the style, stability, and accuracy of the mount and tripod. Telescopes on either very lightweight mounts or non tracking mounts (such as Dobsonians) are capable of only very short exposures such as lunar photographs. If a motor drive is attached to an equatorial mount, even a small lightweight mount is capable of capturing some planetary detail. Larger EQ mounts that utilize very precise tracking and excellent stability are capable of longer exposure deep-sky photography.
Lunar, planetary & long exposure
Length of optical tube
21.8 in.
Weight, optical tube
15.8 lbs.
Additional included accessories
Two 1" and one 2" removable extension tubes, Orion collimation tool
Other features
Ten knife edge baffles, Center marked secondary mirror
In the Box
One two inch long extension ring
Shipping Info
Orders received by noon Pacific Time for in-stock items ship the same business day. Orders received after noon will ship the next business day. When an item is not in-stock we will ship it as soon as it becomes available. Typically in-stock items will ship first and backordered items will follow as soon as they are available. You have the option in check out to request that your order ship complete, if you'd prefer.
A per-item shipping charge (in addition to the standard shipping and handling charge) applies to this product due to its size and weight. This charge varies based on the shipping method.
Standard Delivery: $0.00
As any prolific astrophotographer will tell you, the more light you can gather, the better your astrophotos will turn out. Combine light-gathering prowess with a compact design and an affordable price, and you're likely to end up with our new 8" f/8 Ritchey-Chretien Astrograph. As a leading supplier of affordable imaging equipment and solutions for amateur astronomers, Orion is proud to introduce this highly regarded telescope design used by advanced astrophotographers and professional observatories worldwide — and even by the Hubble Space Telescope!
Previously available only in larger apertures that cost thousands more, the outstanding optical design of the Orion 8" Ritchey-Chretien Astrograph will allow you to capture spectacular, detailed images of deep-sky objects like never before. In contrast to conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to coma away from the center of the field, the Ritchey-Chretien utilizes hyperbolic primary and secondary mirrors to achieve wonderfully flat images that are virtually coma-free. In our 8" model, the mirrors are made of BK-7 optical glass with enhanced aluminum 94% - 96% reflectivity coatings, to provide diffraction-limited performance. Since there are no lenses involved, images are also free from chromatic aberration, which affects all but the finest, most expensive apochromatic refractors.
The Orion 8" Ritchey-Chretien Astrograph Telescope is ideal for use with small CCD-chip cameras such as our award-winning StarShoot line, as well as medium-format CCD and DSLR cameras, for deep-sky and solar system astrophotography. The telescope's wide, fully illuminated flat field produces pinpoint star clarity all the way to the edge of the camera's sensor.
The Orion 8" Ritchey-Chretien Astrograph features a machined, dual-speed (10:1) linear-bearing Crayford-style focuser with an engraved millimeter scale on the drawtube. The robust focuser provides precise fine focus adjustment without slippage or flexure with heavy accessories attached. One 2-inch and two 1-inch extension rings are included for adjusting the focus position for various cameras. Focus travel readily accommodates popular imaging accessories.
Orion Ritchey-Chretien Astrographs have been designed with collimation in mind. With an optical instrument of this caliber, precise optical alignment is of paramount importance. Each Orion RC secondary mirror is precisely center-marked to facilitate collimation and we even include a Cheshire collimation tool to make proper alignment of optics as convenient as possible.
The 21-inch enameled steel optical tube weighs only 15.8 lbs. and features a dovetail mounting bar underneath, for trouble-free setup on medium or large-sized Orion equatorial mounts. The inside of the optical tube is fortified with ten computer-positioned light baffles, and the primary mirror baffle tube and secondary mirror light shield are also highly baffled to ensure maximum image contrast.
Without a doubt, our 8" Ritchey-Chretien Astrograph brings advanced astrophotography performance into the realm of affordability for most amateur astronomers. More affordable than comparably sized apochromatic refractors and without the coma that afflicts Newtonian reflectors, the Orion 8" f/8 Ritchey-Chretien Astrograph Telescope will take your astrophotography to new heights!
Reviews
Orion 8 f/8 Ritchey-Chretien Astrograph Telescope
2
This scope is ideal for the advanced astrophotographer using both small and medium-format CCD cameras and DSLRs. Offers a wide, fully illuminated field and pinpoint star clarity out to camera sensors edge.
Orion 8 f/8 Ritchey-Chretien Astrograph Telescope
2
This scope is ideal for the advanced astrophotographer using both small and medium-format CCD cameras and DSLRs. Offers a wide, fully illuminated field and pinpoint star clarity out to camera sensors edge.
