Orion ShortTube 80 Refractor Telescope Optical Tube Assembly

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Orion ShortTube 80 Refractor Telescope Optical Tube Assembly

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Compact, fast f/5 refractor optical tube assembly excels for use as a guide scope, or for wide-field observations
Coupled with an autoguider camera (sold separately), the ST80 OTA makes guide star acquisition easy and efficient
Multi-coated 80mm aperture, 400mm focal length achromatic optics are housed in an all-metal tube
Its 1.25" aluminum rack-and-pinion focuser has excellent drawtube rigidity with ZERO flexure. Drawtube collar allows attachment of autoguider camera or accessories via their 1.25" nosepiece with dual thumbscrew lock-down or via direct, ultra-secure T-thread attachment.
Sold as optical tube assembly only, without accessories

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Item # 09948b

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It's baack! The affordable optical tube assembly (OTA) version of our Orion ShortTube 80 achromatic refractor telescope is back in our lineup, by popular demand.

Sold without accessories, the ShortTube 80 Refractor Telescope Optical Tube Assembly is ideal for use as a dedicated guide scope for guided astrophotography pursuits. The fast f/5 achromatic optics provide a wide field of view that makes guide star acquisition a breeze. Its all-metal tube features a rack-and-pinion focuser with drawtube tension adjustment and a molded-in dovetail finder scope base that accepts optional Orion finder scopes. Weighing well under 3 lbs., the ShortTube 80 OTA can easily be added to virtually any astrophotography rig without exceeding your equatorial mount's payload capacity.

You'll love this refractor telescope's bright, expansive views. Its multi-coated 80mm achromatic objective lens and short 400mm focal length are perfect for scanning vast vistas. Add your favorite telescope eyepieces, correct-image or mirror diagonal, and finder scope or reflex sight (all sold separately) and you'll have an instrument customized for adventure.

The ShortTube 80 Refractor Telescope Optical Tube Assembly measures 15" in length. Its fixed aluminum dew shield extends a full 3-1/4" out from the objective lens to prevent dew formation and block off-axis glare. Another nice feature: the eyepiece holding collar on the focuser drawtube has two thumbscrews to ensure secure lockdown of your guide camera or diagonal. The end of the collar is even threaded with male T2 threads to allow threaded attachment of a DSLR directly to the focuser (with proper T-ring) for photography.

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 800-447-1001.

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
User level

User level

Beginner Level - Suited for a wide range of uses, these products are simple to operate and set up. Some initial assembly may be required depending on the type of product. Optical instruments with this rating will have very good optical and mechanical quality. Great for families, young people, and folks who don't want to mess with equipment and complexity. Beginning level telescopes will show you countless lunar craters, Saturn's rings and a myriad of star clusters and nebulae! Referring to the manual is recommended.

Intermediate Level - These products offer higher performance and more advanced features than Level 1: Beginner models. They typically take a bit longer to learn and need some set-up or adjustments. But anyone with the slightest technical bent will have no problem getting familiar with these models. Referring to the manual is recommended.

Advanced Level - These products provide the best performance but may require more skill to master and appreciate. Optical instruments with this rating have exceptionally fine optics and mechanics. Some are easy to use but might be on the large or heavy side. Some are intended for specialized uses. These products will appeal to the more technically inclined. Referring to the manual is highly recommended.

Beginner
Optical design

Optical design

Reflector telescopes use a pair of large and small mirrors to direct incoming light to the eyepiece. Refractor telescopes refract, or "bend" incoming light to a focus by means of an objective lens. Cassegrain telescopes, such as Maksutov-Cassegrains, "fold" incoming light using two mirrors and a front "corrector" lens.

Refractor
Optical diameter

Optical diameter

For telescopes, the optical diameter (also known as aperture) is the size of a telescope's main light-collecting lens or primary mirror, measured in millimeters or inches. Telescopes with larger optical diameters collect more light, which leads to an increase in brightness and image resolution compared to smaller instruments.

For binoculars, the optical diameter (also known as objective lens diameter) is the size of each of the front-facing objective lenses of a binocular measured in millimeters. Binoculars with larger objective lenses collect more light, which increases image resolution and brightness. Binoculars with larger objective lenses are recommended for low light situations, and binoculars with at least 50mm or larger objective lenses are recommended for pleasing astronomical observations at night.

80mm
Focal length

Focal length

The distance from the center of a curved mirror or lens at which parallel light rays converge to a single point. The focal length is an inherent specification of a mirror or lens and is one of the factors in determining resultant magnification for a telescope (along with the focal length of the eyepiece being used).

400mm
Focal ratio

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/5.0
Coatings

Coatings

Binocular lenses and prisms are often coated with anti-reflective material to minimize light loss as light travels through the multiple optical surfaces of a typical binocular. Coatings help maximize the amount of light transmitted through each glass surface of a binocular, so as much light as possible reaches the observer's eyes to provide a bright and sharp image.
Good lenses are at least "fully coated," with a single layer of magnesium fluoride coating applied to each air-to-glass lens surface. Multiple layers of coatings are even more effective; the term "multi-coated" means one or more air-to-glass lens surface has multiple coatings. "Fully multi-coated" optics are even better, meaning all lens surfaces have multiple layers of anti-reflective coatings applied for maximum light transmission and optimal image quality.

Multi-coated
Optics type

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.

Air-spaced doublet
Glass material

Glass material

Refractors use glass lenses to focus the light, and the glass material plays an important role in the quality of the resulting image. Standard achromatic refractors routinely use Crown and Flint for the two elements, but more expensive apochromatic refractors can use ED (extra low dispersion) glass for one or more of the lenses. Reflector mirrors are made from glass with different levels of thermal expansion. Standard mirrors are made from material such as Soda-Lime Plate glass and BK-7 glass. Glass with Pyrex or other low thermal expansion material will not change shape as dramatically during the cool-down period, resulting in more stable images during this period.

Crown/Flint
Eyepieces

None
Resolving power

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.

1.45arc*sec
Lowest useful magnification

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.

12x
Highest useful magnification

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.

160x
Highest theoretical magnification

160x
Limiting stellar magnitude

Limiting stellar magnitude

The limiting stellar magnitude is a measure of the faintest star you can see through the telescope.

12.2
Optical quality

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
Finder scope

None
Focuser

1.25" Rack-and-pinion
Mount type

Optical Tube without Mount
Astro-imaging capability

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
Tube material

Aluminum
Length of optical tube

15.0 in.
Weight, optical tube

2.7 lbs.
Other features

Focus lock knob
Warranty

Warranty

This warranty gives you specific legal rights. It is not intended to remove or restrict your other legal rights under applicable local consumer law; your state or national statutory consumer rights governing the sale of consumer goods remain fully applicable.

One year

Shipping Info

Orders received by 1pm Eastern Standard Time for in-stock items ship the same business day. Order 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.

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