Our 8" intelligent Dobsonian telescope has ample aperture and computerized smarts that make it an excellent instrument for any astronomy enthusiast. The Orion SkyQuest XT8i Computerized IntelliScope Dobsonian will give you speedy, push-button access to more than 14,000 fascinating celestial objects on the included IntelliScope Computerized Object Locator. Looking for the Whirlpool Galaxy? Press the button labeled "Messier" then select M51. Whoosh! Wow! In seconds, there it is in the telescope eyepiece, once you?ve pushed the telescope to the position indicated by the handheld Computerized Object Locator. Never been able to find that edge-on galaxy, NGC 891? Tap the "NGC" button, select 891 Whoosh! You?re there. It?s that easy to locate object after object, so many more in an evening than you could ever find before.
Since the Orion IntelliScope Computerized Object Locator does not involve motors, you actively push the telescope following the directions displayed on the handheld IntelliScope controller until the object you?ve selected is centered. The XT8i IntelliScope will actually teach you about locations of objects in the night sky during use as you gently push the telescope from object to object. Instead of relying on power-draining GoTo system motors, the "push-to" IntelliScope XT8i saves energy and expense by running on a single 9-volt battery cell (included).
The Orion SkyQuest XT8i IntelliScope Computerized Dobsonian Telescope is capable of providing you and your family with years of entertainment under the stars. Its 8" (203mm) aperture parabolic primary mirror serves up jaw-dropping images of the planets, cloudy nebulas, star clusters, and galaxies.
Outfitted with great accessories, the XT8i IntelliScope Dobsonian includes two 1.25" telescope eyepieces, a removable eyepiece rack, base handle, collimation cap, and a finder scope. The 25mm and 10mm included Sirius Plossl eyepieces provide magnifications of 48x power and 120x power respectively for a variety of viewing options right out of the box. The included finder scope is our Orion 9x50 Right-Angle Correct-Image model which allows convenient and comfortable aiming and alignment of the telescope. The XT8i Dobsonian?s precise Crayford focuser accepts 2" and 1.25" telescope eyepieces, and provides silky-smooth, backlash-free motion that eliminates image shift, making it easier to achieve the sharpest possible focus.
The XT8i IntelliScope features an enameled steel reflector optical tube which boasts a handy "navigation knob" for easy slewing and repositioning of the telescope. The reflector tube rides on a streamlined, ultra-stable Dobsonian telescope base, which moves smoothly on UHMW polyethylene bearing pads. The Orion CorrecTension system keeps the telescope tube perfectly balanced on the Dobsonian base for simple, effective point-and-view ease of use.
Find out how much fun big-aperture stargazing can be with the ?push-to? Orion SkyQuest XT8i Computerized IntelliScope Dobsonian.
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.
Please note this product was not designed or intended by the manufacturer for use by a child 12 years of age or younger.
Best for viewing
Brighter deep sky
Best for imaging
Lunar & planetary
Finder scope magnification
Finder scope lens diameter
Sirius Plossl 25.0mm, 10.0mm
Magnification with included eyepieces
Highest theoretical magnification
9x50 Correct-image, right angle
Secondary mirror obstruction
Secondary mirror obstruction by diameter
Secondary mirror obstruction by area
Aluminum & Silicon Dioxide
Number of objects in database
Teflon and UHMW bearings
Length of optical tube
Weight, optical tube
Weight, fully assembled
Additional included accessories
IntelliScope computerized object locator HC, Eyepiece rack, Collimation cap
Navigation knob, 2" Crayford focuser
In The Box
Orion SkyQuest XT8i Computerized IntelliScope Optical Tube Assembly
25mm Orion Sirius Plössl telescope eyepiece (1.25")
10mm Orion Sirius Plössl telescope eyepiece (1.25")
Orion 2" - 1.25" eyepiece adapter
IntelliScope object locator hand controller
Orion 9x50 finder scope
Finder scope bracket with O-ring
Telescope eyepiece rack
Eyepiece rack mounting wood screws
Tensioning knob nylon washer
Tensioning knob metal washer
Nylon retaining knob spacer
Handle mounting hex-head screws
Handle mounting screw washers
Azimuth encoder board
Encoder connector board
Top base plate
Ground base plate
Base assembly wood screws
Feet attachment wood screws
Encoder board mounting wood screws
Azimuth axis hex-head screw
Hex lock nut
Altitude bearing cylinders
Altitude bearing cylinder screws
Vertical stop knob
Altitude encoder assembly
Altitude encoder cable (53")
Azimuth encoder cable (24")
Wire retaining clips
Starry Night special edition software
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
3 Day Air Delivery: $261.00
2 Day Delivery: $261.00
Next Day Delivery: $338.00
Does the IntelliScope system use motors?
No, it's human powered! The user moves the scope manually — which is faster quieter, and eats fewer batteries than motorized systems.
If it's not motorized, how does the IntelliScope system actually find objects?
When a target object is selected on the Computerized Object Locator, two directional guide arrows (altitude and azimuth) with numbers are displayed on the illuminated LCD screen. The user moves the telescope in the direction of the arrows until both numbers decrease to 0.0. Then the object will be in the eyepiece's field of view.
Is the IntelliScope Computerized Object Locator compatible with other commercial or home-built telescopes?
No. Critical dimensions and tolerances designed into the IntelliScope base and the encoder-telescope interface would be very difficult to achieve on any other Dobsonian or other telescope system.
Can I use an IntelliScope Dob without the Computerized Object Locator?
Sure! Without the Object Locator the IntelliScope Dobsonian performs like a standard Dobsonian — with a slew of great design and performance features not found on competing Dobsonians.
How many objects are in the IntelliScope database?
There are more than 14,000, enough for a lifetime of observation:
* 7,840 objects from the NGC catalog
* 5,386 objects from the IC catalog
* 110 objects from the Messier catalog
* 837 single, double, multiple, and variable stars
* 99 user-defined objects
* 8 major non-Earth planets
How do you polar-align or initialize the IntelliScope system prior to using it?
The set-up procedure is a piece of cake. First, you rotate the tube to the vertical position and press Enter. Then, you do a simple two-star alignment, where you point the telescope to one bright star, then another, pressing Enter each time. Done! That's all there is to it. The telescope is now properly oriented with the night sky and ready to find objects. The instruction manual has four seasonal star charts that identify the alignment stars you can choose from.
What type of encoders does the IntelliScope system use?
The IntelliScope system uses two magnetic, 9,216-step high-resolution digital encoders. The azimuth encoder comes with the telescope, the altitude encoder comes with the Computerized Object Locator.
How long will the 9-volt battery in the Computerized Object Locator last?
Thirty to 50 hours with typical, intermittent use. Using a dim illumination setting will help conserve battery power.
Can the IntelliScope tube assembly be easily removed from the base for transporting?
Yes. As is explained in the IntelliScope instruction manual, you need only unthread and remove the large knob on each of the two side panels, then the tube assembly can be lifted off the base.
Are IntelliScope Dobsonians suitable for astrophotography?
Not really, since they do not have automatic tracking. However, you can take short exposures of the Moon and planets using afocal, through-the-eyepiece techniques.
Can the IntelliScope be "controlled" by a computer running astronomy software?
Yes. Please see the IntelliScope-to-Starry Night Pro Interface section below for details on configuring your software.
Technical Questions About SkyQuest IntelliScope Telescopes
Note: For general troubleshooting, refer to Appendix A in the IntelliScope Computerized Object Locator instruction manual (IN 229)
What are practical focal lengths to have for eyepieces for my telescope?
To determine what telescope eyepieces you need to get powers in a particular range with your telescope, see our Learning Center article: How to choose Telescope Eyepieces
Does the base need to be level when I use the Object Locator?
No, the base only needs to be leveled once to adjust the vertical stop. Once the vertical stop is properly adjusted, the base does not need to be level.
Why is there a white nylon bushing in the left side panel for the tensioning knob, but no corresponding bushing in the right side panel for the retaining knob?
This is part of the base design. It ensures the Dobsonian altitude bearings will work properly. If a nylon bushing was in the right side panel, the bearing surface would become the nylon bushings themselves instead of the telescope side bearings riding on the UHMW altitude bearing cylinders.
What is the purpose of the black nylon spacer for the retaining knob?
The nylon spacer prevents the retaining knob from pinching the right side panel of the base. If the spacer is removed, the retaining knob can be tightened so that it will come into contact with the right side panel and prevent smooth altitude motion of the telescope.
Is the brass azimuth bushing supposed to rotate with the top baseplate?
No, it is not. If it does, the azimuth encoder will not function reliably. If rotation of the bushing is observed, the hex lock nut on the azimuth bolt is probably not tight enough; it should be tightened about 1/4 turn past the point where the fender washer underneath it can no longer be moved by your fingers. It is also possible that the fit between the bushing and top baseplate is too tight. If you cannot install and remove the brass bushing from the top baseplate with your fingers, then roll up a piece of sandpaper and sand the inner wall of the central hole in the top baseplate until you can.
What is the material for the altitude bearing cylinders? I thought UHMW was white in color?
The altitude bearings cylinders are indeed made of UHMW. We have added black dye to the material to match the color of the base.
Can the IntelliScope Dobsonians be used in conjunction with an equatorial platform?
Yes, the IntelliScope Dobs are fully functional with equatorial platforms. This requires turning off the internal clock of the Object Locator, which is a menu option for the "hidden functions."
What can I do to ensure best pointing accuracy?
Besides proper assembly, make sure the vertical stop is precisely adjusted by means of a carpenter's level. Also, use a high-powered illuminated reticle eyepiece to center the alignment stars.
Why do the azimuth encoder and encoder connector board come with the telescope, but the altitude encoder comes with the Object Locator?
The azimuth encoder is needed for proper assembly of the base, regardless of whether the Object Locator is used or not. The altitude encoder is not needed if the Object Locator is not used. The encoder connector board is not needed if the Object Locator is not used, but it acts as a cover for the modular jack hole in the left side panel.
My encoder disk(s) has some marks and/or scratches on the magnetic ring. Should I be concerned?
No, the magnetic rings of the encoder disks are not affected by impressions or scratches. If the magnetic ring is torn, contact Orion Customer Service.
What is the pointing accuracy I should expect with the IntelliScope system?
If properly assembled and aligned, the Object Locator will locate objects to better than 0.5°. This will always place the desired object within the field of view of the supplied 25mm Sirius Plossl eyepiece.
Will the IntelliScope system perform in extremely cold weather?
At temperatures colder than 0° F, 9V DC batteries typically do not provide enough power to operate most devices. This is the case with the Object Locator. If it's that cold out, you should be inside with a hot beverage!
I wish to make some modifications to the bearings of my IntelliScope Dobsonian. Is this okay?
No, modifications to the bearings are not recommended, as the IntelliScope system may be adversely affected. The spacings and tolerances of the parts are critical, and all modifications are made at the customer's own risk. If the telescope is properly assembled, there should be no need to modify the bearings.
Will time elapsing between alignment star sightings affect pointing accuracy?
Generally, no. It should not take more than a couple of minutes between entering the first and second alignment stars, which will not affect pointing accuracy. You should identify two available alignment stars in the sky before even turning the Object Locator on. If more than 5 minutes elapse between entering alignment stars, then pointing accuracy may be somewhat diminished.
What is Orion’s Standard One Year Limited Warranty?
Orion warranties against defects in materials or workmanship for a period of one year from the date of purchase for Orion brand products. This warranty is for the benefit of the original retail purchaser only. During this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s option, any warranted instrument that proves to be defective, provided it is returned postage paid to: Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076. If the product is not registered, proof of purchase (such as a copy of the original invoice) is required. This warranty does not apply if, in Orion’s judgment, the instrument has been abused, mishandled, or modified, nor does it apply to normal wear and tear. This warranty gives customer’s specific legal rights, and you may also have other rights, which vary from state to state. For further warranty service information, contact: Customer Service Department, Orion Telescopes & Binoculars, 89 Hangar Way, Watsonville CA 95076; (800) 676-1343.
Some items may be covered by a warranty period shorter or longer than the standard one year warranty. Specific warranty information is available on the product detail page of the website
How can I check the collimation of my reflector?
Collimation is the process of adjusting the telescope’s mirrors so they are perfectly aligned with one another. Your telescope’s optics were aligned at the factory, and should not need much adjustment unless the telescope is handled roughly. Mirror alignment is important to ensure the peak performance of your telescope, so it should be checked regularly. Collimation is relatively easy to do and can be done in daylight. To check collimation, remove the eyepiece and look down the focuser drawtube. You should see the secondary mirror centered in the drawtube, as well as the reflection of the primary mirror centered in the secondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror. If anything is off-center, proceed with the collimation procedure. (insert the hyperlink to the collimation procedure) The faster the f/ratio of your telescope, the more critical the collimation accuracy.
How do I use the Orion Collimation Cap and the mirror center mark?
The Orion collimation cap is a simple cap that fits on the focuser drawtube like a dust cap, but has a hole in the center and a silver bottom. This helps center your eye so that collimation is easy to perform. Orion telescopes that have a collimation cap included also have a primary mirror that is marked with a circle at its exact center. This “center mark” allows you to achieve a precise collimation of the primary mirror; you don’t have to guess where the center of the mirror is. You simply adjust the mirror position until the reflection of the hole in the collimation cap is centered in the ring. The center mark is also required for best results when using other collimating devices, such as Orion’s LaserMate Collimator, obviating the need to remove the primary mirror and mark it yourself. Note: The center ring sticker need not ever be removed from the primary mirror. Because it lies directly in the shadow of the secondary mirror, its presence in no way adversely affects the optical performance of the telescope or the image quality. That might seem counterintuitive, but its true!
Can I center the secondary mirror under the focuser with the aid of the Orion LaserMate?
You can, but it requires marking the center of the telescope’s secondary mirror in the same way the center of the telescope’s primary mirror was marked. This is generally undesirable due to the large area of the supplied collimation targets compared to the total area of the secondary mirror. Since centering the secondary mirror under the focuser is an adjustment that very rarely, if ever, needs to be done, we recommend simply making this adjustment by eye. We’ve tried it both ways and it is just as easy to do it without the Orion LaserMate.
How do I align the secondary mirror with the collimation cap?
With the collimation cap in place, look through the hole in the cap at the secondary mirror. Ignore the reflections for the time being. The secondary mirror itself should be centered in the focuser drawtube, in the direction parallel to the length of the telescope. If it isn’t, it must be adjusted. Typically, this adjustment will rarely, if ever, need to be done. It helps to adjust the secondary mirror in a brightly lit room with the telescope pointed towards a bright surface, such as white paper or wall. Also placing a piece of white paper in the telescope tube opposite the focuser (in other words, on the other side of the secondary mirror) will also be helpful in collimating the secondary mirror. Using a 2mm Allen wrench, loosen the three small alignment set screws in the center hub of the 4-vaned spider several turns. Now hold the mirror holder stationary (be careful not to touch the surface of the mirror), while turning the center screw with a Phillips head screwdriver. Turning the screw clockwise will move the secondary mirror toward the front opening of the optical tube, while turning the screw counter-clockwise will move the secondary mirror toward the primary mirror. Note: When making these adjustments, be careful not to stress the telescope’s spider vanes or they may bend. When the secondary mirror is centered in the focuser draw-tube, rotate the secondary mirror holder until the reflection of the primary mirror is as centered in the secondary mirror as possible. It may not be perfectly centered, but that is OK. Now tighten the three small alignment screws equally to secure the secondary mirror in that position. If the entire primary mirror reflection is not visible in the secondary mirror, you will need to adjust the tilt of the secondary mirror. This is done by alternately loosening one of the three alignment set screws while tightening the other two. The goal is to center the primary mirror reflection in the secondary mirror. Don’t worry that the reflection of the secondary mirror (the smallest circle, with the collimation cap “dot” in the center) is off-center. You will fix that when aligning the primary mirror. Alternative: Some people prefer to remove the primary mirror completely from the telescope when aligning the secondary mirror, especially if the primary mirror needs to be removed anyway to be center-marked. It may help to have no reflections and align the secondary on the edge of the telescope wall.
How do I align the primary mirror with the collimation cap and center-marked mirror?
The telescope’s primary mirror will need adjustment if the secondary mirror is centered under the focuser and the reflection of the primary mirror is centered in the secondary mirror, but the small reflection of the secondary mirror (with the “dot” of the collimation cap) is off-center. The tilt of the primary mirror is adjusted with the larger collimation screws on the back end of the telescope’s optical tube. The other smaller screws lock the mirror’s position in place; these thumbscrews must be loosened before any collimation adjustments can be made to the primary mirror. To start, loosen the smaller thumbscrews that lock the primary mirror in place a few turns each. Use a screwdriver in the slots, if necessary. Now, try tightening or loosening one of the larger collimation screws with your fingers Look into the focuser and see if the secondary mirror reflection has moved closer to the center of the primary. You can tell this easily with the collimation cap and mirror center mark by simply watching to see if the “dot” of the collimation cap is moving closer or further away from the “ring” on the center of the primary mirror mark. When you have the dot centered as much as is possible in the ring, your primary mirror is collimated. Re-tighten the locking thumbscrews. Alternative: If you loosen one or more of the bolts too much, it won’t move the mirror. Some people prefer to pre-load the collimation screws by tightening them all down and adjust by loosening each one in turn. This way you don’t run-out of threads and have a loose collimation screw. The disadvantage to this approach is that you have completely un-collimated the scope and are starting from the beginning.
Is the LaserMate Collimator dangerous?
The LaserMate emits laser radiation, so it is important not to shine the beam into your or anyone’s eye. During the collimation procedure, it is also important to avoid direct reflections of the laser beam into your eye. Rather, look only at off-axis reflections to determine the position of the laser spot on the mirrors. It is safe to view the laser when it is reflected off a surface that will diffuse the light, such as the bottom surface of the LaserMate. It is also safe to view the reflection off a mirror surface as long as the beam is not directed into your eye. Because of the potential danger from the laser beam, store your LaserMate out of the reach of children.
How do I care for and maintain my Collimating Eyepiece ?
Because there are no lenses in the Collimating Eyepiece, care and maintenance is minimal. It is a good idea to remove any obvious dirt on the inside or outside of the eyepiece so that the dirt does not get into the telescope tube during the collimation process. To clean the eyepiece, use a blower bulb or a moist cotton swab to remove dirt from inside the barrel, and simply wipe the outside with a damp cloth. Make sure not to disturb the crosshairs, as bending or breaking may result. Your best bet is to store the Collimating Eyepiece in a case for easy access. If you drop the eyepiece, don’t worry. It’s made of machined metal, so it’s very durable, and small scratches or dents will not affect usage. Should the metal insert containing the sight hole become loose, reposition the insert so that the polished 45°-angle flat faces directly toward the cut-away opening in the barrel, then tighten the tiny set screw near the top of the barrel with a watch-repair screwdriver.
How do I align a finder scope?
Before you use the finder scope, it must be precisely aligned with the telescope so they both point to exactly the same spot. Alignment is easiest to do in daylight, rather than at night under the stars. First,insert a low power telescope eyepiece (a 25mm eyepiece will work great) into the telescope’s focuser. Then point the telescope at a discrete object such as the top of a telephone pole or a street sign that is at least a quarter-mile away. Position the telescope so the target object appears in the very center of the field of view when you look into the eyepiece. Now look through the finder scope. Is the object centered on the finder scope’s crosshairs? If not, hopefully it will be visible somewhere in the field of view, so only small turns of the finder scope bracket’s alignment thumb screws will be needed. Otherwise you’ll have to make larger turns to the alignment thumb screws to redirect the aim of the finder scope. Use the alignment thumb screws to center the object on the crosshairs of the finder scope. Then look again into the telescope’s eyepiece and see if it is still centered there too. If it isn’t, repeat the entire process, making sure not to move the telescope while adjusting the alignment of the finder scope. Finder scopes can come out of alignment during transport or when removed from the telescope, so check its alignment before each observing session.
How do I focus the finder scope?
If, when looking through the finder scope, you notice that the image is fuzzy, you will need to focus the finder scope for your eyes. Different finder scopes focus differently; most Orion finder scopes include a lock ring near the objective and focus as follows:
1. Loosen the lock ring that is located behind the finder’s objective lens cell
2. Screw the objective lens cell in or out until the image appears sharp.
3. Tighten the lock ring behind the lens cell. If there is no lock ring the finder scope is focused by rotating the eyepiece.
Once the finder scope is now focused it should not need focusing again for your eyes.
How do I calculate the magnification (power) of a telescope?
"To calculate the magnification, or power, of a telescope with an eyepiece, simply divide the focal length of the telescope by the focal length of the eyepiece. Magnification = telescope focal length ÷ eyepiece focal length. For example, the Orion 6" Dobsonian Telescope, which has a focal length of 1200mm, used in combination with the supplied 25mm eyepiece, yields a power of: 1200 ÷ 25 = 48x.
It is desirable to have a range of telescope eyepieces of different focal lengths to allow viewing over a range of magnifications. It is not uncommon for an observer to own five or more eyepieces. Orion offers many different eyepieces of varying focal lengths.
Every telescope has a theoretical limit of power of about 50x per inch of aperture (i.e. 300x for the Orion SkyQuest 6"). Atmospheric conditions will limit the usefullness of magnification and cause views to become blurred. Claims of higher power by some telescope manufacturers are a misleading advertising gimmick and should be dismissed. Keep in mind that at higher powers, an image will always be dimmer and less sharp (this is a fundamental law of optics). With every doubling of magnification you lose half the image brightness and three-fourths of the image sharpness. The steadiness of the air (the “seeing”) can also limit how much magnification an image can tolerate. Always start viewing with your lowest-power (longest focal length) eyepiece in the telescope. It’s best to begin observing with the lowest-power eyepiece, because it will typically provide the widest true field of view, which will make finding and centering objects much easier After you have located and centered an object, you can try switching to a higher-power eyepiece to ferret out more detail, if atmospheric conditions permit. If the image you see is not crisp and steady, reduce the magnification by switching to a longer focal length eyepiece. As a general rule, a small but well-resolved image will show more detail and provide a more enjoyable view than a dim and fuzzy, over-magnified image.
What are practical focal lengths to have for eyepieces for my telescope?
To determine what telescope eyepieces you need to get powers in a particular range with your telescope, see our Learning Center article: How to choose Telescope Eyepieces
Why do Orion telescopes have less power than the telescope at department stores?
Advertising claims for high magnification of 400X, 600X, etc., are very misleading. The practical limit is 50X per inch of aperture, or 120X for a typical 60mm telescope. Higher powers are useless, and serve only to fool the unwary into thinking that magnification is somehow related to quality of performance. It is not.
How do I get started with astronomical viewing?
When choosing a location for nighttime stargazing, make it as far away from city lights as possible. Light-polluted skies greatly reduce what can be seen with the telescope. Also, give your eyes at least 20 minutes to dark-adapt to the night sky. You’ll be surprised at how many more stars you will see! Use a red flashlight, to see what you’re doing at the telescope, or to read star charts. Red light will not spoil your dark-adapted night vision as readily as white light will. To find celestial objects with your telescope, you first need to become reasonably familiar with the night sky. Unless you know how to recognize the constellation Orion, for instance, you won’t have much luck locating the Orion Nebula. A simple planisphere, or star wheel, can be a valuable tool for learning the constellations and seeing which ones are visible in the sky on a given night. A good star chart or atlas, like the Orion DeepMap 600, can come in handy for helping locate interesting objects among the dizzying multitude of stars overhead. Except for the Moon and the brighter planets, it is pretty time-consuming and frustrating to hunt for objects randomly, without knowing where to look. It is best to have specific targets in mind before you begin looking through the eyepiece. Practice makes perfect. After a few nights, this will begin to “click” and star-hopping will become easier.
What is the best telescope for a beginner?
The “best scope” for anyone is highly subjective and varies based on the person who will be using the telescope. Their level of interest in the hobby, their aptitude for "the technical", the level of investment that you want to make, and the ability to carry differing weights. For more detailed information on this topic see our Learning Center article: How to Choose a Telescope
How big a telescope do I need?
For viewing craters on the Moon, the rings of Saturn, and Jupiter with its four bright moons, a 60mm or 70mm refractor or a 3-inch reflector telescope does a good job. An 80mm to 90mm refractor or 4.5-inch or 6-inch reflector will show more planetary and lunar detail as well as glowing nebulas and sparkling star clusters. Under dark, non-light-polluted skies, a big scope—8-inch diameter or more—will serve up magnificent images of fainter clusters, galaxies, and nebulas. The larger the telescope, the more detail you will see. But don’t bite off more than you can chew, size-wise. Before you buy, consider carefully a telescope’s size and weight. Make sure you can comfortably lift and transport it, and that you have room indoors to store it. For more detailed information on this topic see our Learning Center article: Choosing a Telescope for Astronomy - The long Version
Why would I want a manual scope when I can get a Go-To scope?
For the novice stargazer, buying a computer-controlled telescope with a small aperture puts a lot of money into the mechanical and database components of the telescope to locate objects that you can’t see with the optics of the telescope. Someone who is inexperienced with astronomy and night sky will spend their time pouring over instruction manuals and text scrolling across a screen instead of exploring the night sky, studying the stars and their patterns and learning how to locate to binary stars and nebula. Our advise . . .go for bigger aperture.
What causes dim or distorted images?
Too much magnification
Keep in mind that at higher powers, an image will always be dimmer and less sharp (this is a fundamental law of optics). The steadiness of the air, the seeing, can also limit how much magnification an image can tolerate. Always start viewing with your lowest-power (longest focal length) eyepiece in the telescope. It’s best to begin observing with the lowest-power eyepiece, because it will typically provide the widest true field of view, which will make finding and centering objects much easier After you have located and centered an object, you can try switching to a higher-power eyepiece to ferret out more detail, if atmospheric conditions permit. If the image you see is not crisp and steady, reduce the magnification by switching to a longer focal length telescope eyepiece. As a general rule, a small but well-resolved image will show more detail and provide a more enjoyable view than a dim and fuzzy, over-magnified image. As a rule of thumb, it is not recommended to exceed 2x per mm of aperture.
Atmospheric conditions aren’t optimal.
Atmospheric conditions vary significantly from night to night, even hour to hour . “Seeing” refers to the steadiness of the Earth’s atmosphere at a given time. In conditions of poor seeing, atmospheric turbulence causes objects viewed through the telescope to “boil.” If, when you look up at the sky with just your eyes, the stars are twinkling noticeably, the seeing is bad and you will be limited to viewing with low powers (bad seeing affects images at high powers more severely). Seeing is best overhead, worst at the horizon. Also, seeing generally gets better after midnight, when much of the heat absorbed by the Earth during the day has radiated off into space. It’s best, although perhaps less convenient, to escape the light-polluted city sky in favor of darker country skies.
Viewing through a glass window open or closed.
Avoid observing from indoors through an open (or closed) window, because the temperature difference between the indoor and outdoor air, reflections and imperfections in the glass, will cause image blurring and distortion.
Telescope not at thermal equilibrium.
All optical instruments need time to reach “thermal equilibrium.” The bigger the instrument and the larger the temperature change, the more time is needed. Allow at least a half-hour for your telescope to cool to the temperature outdoors. In very cold climates (below freezing), it is essential to store the telescope as cold as possible. If it has to adjust to more than a 40 degrees temperature change, allow at least one hour. Time to adjust varies depending on the scope type and aperture.
Make sure you are not looking over buildings, pavement, or any other source of heat, which will radiate away at night, causing “heat wave” disturbances that will distort the image you see through the telescope.
Does the atmosphere play a role in how good the quality of the image will be?
Atmospheric conditions play a huge part in quality of viewing. In conditions of good “seeing”, star twinkling is minimal and objects appear steady in the eyepiece. Seeing is best over-head, worst at the horizon. Also, seeing generally gets better after midnight, when much of the heat absorbed by the Earth during the day has radiated off into space. Typically, seeing conditions will be better at sites that have an altitude over about 3000 feet. Altitude helps because it decreases the amount of distortion causing atmosphere you are looking through. A good way to judge if the seeing is good or not is to look at bright stars about 40 degrees above the horizon. If the stars appear to “twinkle”, the atmosphere is significantly distorting the incoming light, and views at high magnifications will not appear sharp. If the stars appear steady and do not twinkle, seeing conditions are probably good and higher magnifications will be possible. Also, seeing conditions are typically poor during the day. This is because the heat from the Sun warms the air and causes turbulence. Good “transparency” is especially important for observing faint objects. It simply means the air is free of moisture, smoke, and dust. These tend to scatter light, which reduces an object’s brightness. One good way to tell if conditions are good is by how many stars you can see with your naked eye. If you cannot see stars of magnitude 3.5 or dimmer then conditions are poor. Magnitude is a measure of how bright a star is, the brighter a star is, the lower its magnitude will be. A good star to remember for this is Megrez (mag. 3.4), which is the star in the “Big Dipper” connecting the handle to the “dipper”. If you cannot see Megrez, then you have fog, haze, clouds, smog, light pollution or other conditions that are hindering your viewing. Another hint: Good seeing can vary minute to minute. Watch the planets for a while to pick-up those moments of good seeing.
How long will it take my eyes to dark adapt?
Do not expect to go from a lighted house into the darkness of the outdoors at night and immediately see faint nebulas, galaxies, and star clusters—or even very many stars, for that matter. Your eyes take about 30 minutes to reach perhaps 80 percent of their full dark-adapted sensitivity. Many observers notice improvements after several hours of total darkness. As your eyes become dark-adapted, more stars will glimmer into view and you will be able to see fainter details in objects you view in your telescope. So give yourself at least a little while to get used to the dark before you begin observing. To see what you are doing in the darkness, use a red light flashlight rather than a white light. Red light does not spoil your eyes’ dark adaptation like white light does. A flashlight with a red LED light is ideal, or you can cover the front of a regular flashlight with red cellophane or paper. Beware, too, that nearby porch and streetlights and automobile headlights will spoil your night vision. Your eyes can take at least 1/2 hour to re-adjust.
How do I see the best detail on the surface of the Moon?
The Moon, with its rocky, cratered surface, is one of the easiest and most interesting subjects to observe with your telescope. The myriad craters, rilles, and jagged mountain formations offer endless fascination. The best time to observe the Moon is during a partial phase, that is, when the Moon is not full. During partial phases, shadows cast by crater walls and mountain peaks along the border between the dark and light portions of the lunar disk highlight the surface relief. A full Moon is too bright and devoid of surface shadows to yield a pleasing view. Try using an Orion Moon filter to dim the Moon when it is too bright; it simply threads onto the bottom of the eyepiece, you’ll see much more detail.
How do I best view Deep-Sky Objects?
Most deep-sky objects are very faint, so it is important that you find an observing site well away from light pollution. Take plenty of time to let your eyes adjust to the darkness. Don’t expect these objects to appear like the photographs you see in books and magazines; most will look like dim gray “ghosts.” (Our eyes are not sensitive enough to see color in deep-sky objects except in few of the brightest ones.) But as you become more experienced and your observing skills improve, you will be able to coax out more and more intricate details. And definitely use your low-power telescope eyepieces to get a wide field-of-view for the largest of the deep-sky objects.
What will the planets look like through the telescope?
The planets don’t stay put like stars do (they don’t have fixed R.A. and Dec. coordinates), so you will need to refer to the Orion Star Chart on our website. Venus, Mars, Jupiter, and Saturn are among the brightest objects in the sky after the Sun and the Moon. All four of these planets are not normally visible in the sky at one time, but chances are one or two of them will be.
JUPITER: The largest planetJupiter, is a great subject to observe. You can see the disk of the giant planet and watch the ever-changing positions of its four largest moons, Io, Callisto, Europa, and Ganymede. If atmospheric conditions are good, you may be able to resolve thin cloud bands on the planet’s disk.
SATURN: The ringed planet is a breathtaking sight when it is well positioned. The tilt angle of the rings varies over a period of many years; sometimes they are seen edge-on, while at other times they are broadside and look like giant “ears” on each side of Saturn’s disk. A steady atmosphere (good seeing) is necessary for a good view. You may probably see a tiny, bright “star” close by; that’s Saturn’s brightest moon, Titan.
VENUS: At its brightest, Venus is the most luminous object in the sky, excluding the Sun and the Moon. It is so bright that sometimes it is visible to the naked eye during full daylight! Ironically, Venus appears as a thin crescent, not a full disk, when at its peak brightness. Because it is so close to the Sun, it never wanders too far from the morning or evening horizon. No surface markings can be seen on Venus, which is always shrouded in dense clouds. Sometimes using a color filter will lessen the glare of Venus and help you see the crescent.
MARS: If atmospheric conditions are good, you may be able to see some subtle surface detail on the Red Planet, possibly even the polar ice cap. Mars makes a close approach to Earth every two years; during those approaches its disk is larger and thus more favorable for viewing. For more detailed information on this topic see our Learning Center article: What Will You See Through a Telescope
How do I Find Deep-sky Objects by Starhopping?
"Starhopping, as it is called by astronomers, is perhaps the simplest way to hunt down objects to view in the night sky. It entails first pointing the telescope at a star close to the object you wish to observe, and then progressing to other stars closer and closer to the object until it is in the field of view of the eyepiece. It is a very intuitive technique that has been employed for hundreds of years by professional and amateur astronomers alike. Keep in mind, as with any new task, that starhopping may seem challenging at first, but will become easier over time and with practice. To starhop, only a minimal amount of additional equipment is necessary. A star chart or atlas that shows stars to at least magnitude 5 is required. Select one that shows the positions of many deep-sky objects, so you will have a lot of options to choose from. If you do not know the positions of the constellations in the night sky, you will need to get a planisphere to identify them. Start by choosing bright objects to view. The brightness of an object is measured by its visual magnitude; the brighter an object, the lower its magnitude. Choose an object with a visual magnitude of 9 or lower. Many beginners start with the Messier objects, which represent some of the best and brightest deep-sky objects, first catalogued about 200 years ago by the French astronomer Charles Messier. Determine in which constellation the object lies. Now, find the constellation in the sky. If you do not recognize the constellation on sight, consult a planisphere. The planisphere gives an all-sky view and shows which constellations are visible on a given night at a given time. Now look at your star chart and find the brightest star in the constellation that is near the object that you are trying to find. Using the finder scope, point the telescope at this star and center it on the crosshairs Next, look again at the star chart and find another suitably bright star near the bright star currently centered in the finder. Keep in mind that the field of view of the finder scope is between 5° - 7°, so you should choose a star that is no more than 7° from the first star, if possible. Move the telescope slightly, until the telescope is centered on the new star. Continue using stars as guideposts in this way until you are the approximate position of the object you are trying to find. Look in the telescope’s eyepiece, and the object should be somewhere within the field of view. If it’s not, sweep the telescope carefully around the immediate vicinity until the object is found. If you have trouble finding the object, start the starhop again from the brightest star near the object you wish to view. This time, be sure the stars indicated on the star chart are in fact the stars you are centering in the finder scope and telescope eyepiece. Remember the telescope and the finder scope will give you inverted images (unless you are using a correct image finder scope), keep this in mind when you are starhopping from star to star. Observing Hint: Always use your lowest powered eyepiece in your telescope when starhopping . This will give you the widest possible field of view. "
Can I wear my glasses when using a telescope?
If you wear eyeglasses, you may be able to keep them on while you observe, if your telescope eyepieces have enough “eye relief” to allow you to see the whole field of view. You can find out by looking through the eyepiece first with your glasses on and then with them off, and see if the glasses restrict the view to only a portion of the full field. If they do, you can easily observe with your glasses off by just refocusing the telescope the needed amount. If your eyes are astigmatic, images will probably appear the best with glasses on. This is because a telescope’s focuser can accommodate for nearsightedness or farsightedness, but not astigmatism. If you have to wear your glasses while observing and cannot see the entire field of view, you may want to purchase additional eyepieces that have longer eye relief.
What will a star look like through a telescope?
Stars will appear like twinkling points of light in the telescope. Even the largest telescopes cannot magnify stars to appear as anything more than points of light. You can, however, enjoy the different colors of the stars and locate many pretty double and multiple stars. The famous “Double-Double” in the constellation Lyra and the gorgeous two-color double star Albireo in Cygnus are favorites. Defocusing the image of a star slightly can help bring out its color. For more detailed information on this topic see our Learning Center article: Stars and Deep Sky Objects >
Is there an eyepiece available that will rotate the image so that it can be used for scenic viewing?
We carry correct-image prism diagonals which provide right-side up non-reversed images in refractor and cassegrain telescopes. It is not possible to correct the image orientation in a reflector telescope.
How do I clean the reflecting mirror of my telescope?
You should not have to clean the telescope’s mirrors very often; normally once every other year or even less often. Covering the telescope with the dust cover when it is not in use will prevent dust from accumulating on the mirrors. Improper cleaning can scratch mirror coatings, so the fewer times you have to clean the mirrors, the better. Small specks of dust or flecks of paint have virtually no effect on the visual performance of the telescope. The large primary mirror and the elliptical secondary mirror of your telescope are front-surface aluminized and over-coated with hard silicon dioxide, which prevents the aluminum from oxidizing. These coatings normally last through many years of use before requiring re-coating. To clean the secondary mirror, first remove it from the telescope. Do this by holding the secondary mirror holder stationary while turning the center Phillips-head screw. Be careful, there is a spring between the secondary mirror holder and the phillips head screw. Be sure that it will not fall into the optical tube and hit the primary mirror. Handle the mirror by its holder; do not touch the mirror surface. Then follow the same procedure described below for cleaning the primary mirror. To clean the primary mirror, carefully remove the mirror cell from the telescope and remove the mirror from the mirror cell. If you have an Orion telescope, instructions to remove the primary mirror are included in your instruction manual. Do not touch the surface of the mirror with your fingers. Lift the mirror carefully by the edges. Set the mirror on top, face up, of a clean soft towel. Fill a clean sink, free of abrasive cleanser, with room-temperature water, a few drops of mild liquid dishwashing soap, and, if possible, a capful of rubbing alcohol. Submerge the mirror (aluminized face up) in the water and let it soak for a few minutes (or hours if it’s a very dirty mirror). Wipe the mirror under water with clean cotton balls, using extremely light pressure and stroking in straight line across the mirror. Use one ball for each wipe across the mirror. Then rinse the mirror under a stream of lukewarm water. Before drying, tip the mirror to a 45 degree angle and pour a bottle of distilled water over the mirror. This will prevent any tap water dissolved solids from remaining on the mirror. Any particles on the surface can be swabbed gently with a series of cotton balls, each used just one time. Dry the mirror in a stream of air (a “blower bulb” works great), or remove any stray drops of water with the corner of a paper towel. Water will run off a clean surface. Cover the mirror surface with tissue, and leave the mirror in a warm area until it is completely dry before replacing in the mirror cell and telescope.
Does my telescope require time to cool down?
As a general rule, telescopes should be allowed to cool down (or warm up) before they are used. If you bring optics from a warm air to cold air (or vice versa) without giving it time to reach thermal equilibrium, your telescope will give you distorted views. Allow your telescope 30 minutes to an hour to reach the temperature of the outdoors before using. When brining your telescope from cool temperatures to warm temperatures, leave any protective caps off until the telescope has warmed-up to prevent condensation. Storing your telescope in the garage or shed where the temperature is closer to the outside temperature will reduce cool down times.
SkyQuest Classic Tube Balance
Dobsonians are designed to balance with standard supplied accessories, such as an eyepiece and a finder scope. But if you want to use a larger finder scope or a heavier eyepiece the telescope may no longer be properly balanced, and will not hold its position properly. This makes the telescope difficult to use, since it is critical that it hold its position (when not purposefully moved) to keep objects centered in the field of vision. Traditional Dobsonian designs expect the user to compensate for heavier accessories by adding weight to the opposite end of the telescope tube such as counterweighting systems. The CorrecTension Friction Optimization system of the SkyQuest Dobsonians, however, solves the finicky balance problem. The spring coils pull the tube down onto the base, thereby increasing the friction on the altitude bearing pads. With CorrecTension, the added weight of small front-end loads will not adversely affect the balance of the telescope. If you install an array of heavier accessories onto your SkyQuest’s optical tube, you may need at some point to counterbalance the telescope with a counterweight system.
How do I focus my reflector telescope?
First, insert a low power telescope eyepiece (25mm will work great) in the focuser and point the telescope in the general direction of an object at least a 1/4 mile away. With your fingers, slowly rotate one of the focus knobs until the object comes into sharp focus. Go a little bit beyond sharp focus until the object starts to blur again, then reverse the direction of the knob, just to make sure you’ve hit the exact focus point.
NOTE: The image in the telescope will appear rotated 180° (upside-down and reversed left-to-right). This is normal for astronomical telescopes. The finder scope view will also be rotated 180°, unless you have a correct-image finder. If your finder scope view is rotated 180°, just rotate your star map to match. If you have trouble focusing, rotate the focus knob so the drawtube is in as far as it will go. Now look through the eyepiece while slowly rotating the focusing knob in the opposite direction. You should soon see the point at which focus is reached. You will have to re-adjust the focus when aiming at subjects of varying distances, or after changing eyepieces. For more detailed information on this topic see our Learning Center article: The Star Party:
How To Focus Your Telescopes
How do I track an object in the sky with my Orion dobsonian telescope?
The Earth is constantly rotating about its polar axis, completing one full rotation every 24 hours; this is what defines a “day.” We do not feel the Earth rotating, but we can tell that it is at night by seeing the apparent movement of stars from east to west. This movement translates to 15° per hour or 30x the diameter of the moon. This is called the sidereal rate. When you observe any astronomical object, you are watching a moving target. This means the telescope’s position must be continuously updated over time to keep an object in the field of view. This is easy to do with the Orion SkyQuest Dobsonians because of its smooth motions on both axes. As the object moves off toward the edge of the field of view, you just lightly nudge the telescope to bring it back to the center. You will notice that it is more difficult to “track” objects when the telescope tube is aimed nearly straight up. This is inherent to the basic design of the Dobsonian, and stems from the fact that there is very little mechanical leverage to move in azimuth when the tube is in a near vertical position. To gain more leverage, try grasping the tube close to the altitude side bearings with both hands. Also, by waiting an hour anything that is straight-up, won’t be. Remember that objects appear to move across the field of view faster at higher magnifications. This is because the field of view becomes narrower.
Can I do astrophotography with my Orion SkyQuest XT?
SkyQuest XT Dobsonians are designed for visual, not photographic use. The Dobsonian mount is not an equatorial type mount, so it cannot be motor driven for long exposure astrophotography. You can take great shots of the moon with film or digital camera, but that is the extent of astrophotography with a Dobsonian telescope.
I recently purchased a solar filter for my telescope and can’t see anything with it. Any suggestions?
One of the problems with a solar filter on a telescope is that it’s a bit tricky to aim it at the sun. You can’t look through the finder to point the scope or you’ll cause injury to your eye. So, cap off or remove the finder. Also, because with the very dark filter on the front if the sun is slightly outside the field of view of the eyepiece you’ll see pitch blackness in the field. With the solar filter properly mounted, try looking at the shadow of the optical tube on the ground, move the tube until the shadow is at a minimum. You’ll be pointed at the sun, or at least close enough to find it with a little sweeping and a low-power eyepiece to bring it into view. It can be difficult, even with the shadow method. An other trick to try after you’ve got it close with the shadow if your still not having any luck getting the sun in the field. . . take the eyepiece out of the focuser. Then look into the focuser. . . you won’t see an image but when the sun gets close you’ll see a flicker of brightness coming through the mirrors. Then pop the eyepiece back in and you should have it.
IntelliScope-to-Starry Night Pro Interface
* To use Starry Night Pro as the graphical interface for controlling your IntelliScope, you will need to download the ASCOM driver update after installing the Starry Night Pro software (see below). ASCOM version 4.1 (or later) is required, and is available at: http://download.ascom-standards.org/ascom41.exe
* Works on Windows Vista, Windows XP (not 2000, NT, ME or 98) and Macintosh 10.3 or higher.
Install the Starry Night Pro software. Follow all prompts and change discs as necessary. Allow Starry Night Pro to install QuickTime and the ASCOM v3.0 driver. Adobe Acrobat is not necessary if you already have a .pdf reader on your computer. Do not restart the computer after the ASCOM (v3.0) driver is installed; complete the Starry Night Pro installation first. When the Starry Night Pro installation is complete, then restart your computer. Then download the ASCOM (v4.1) update, and restart your computer again.
You are now ready to configure Starry Night Pro for use with the IntelliScope system:
1. Open the Starry Night Pro program on your computer.
2. Click on the tab marked "Telescope" at the bottom of the vertical row of tabs on the left side of the main display screen.
3. Click on "Configure." The ASCOM Telescope Chooser will pop-up.
4. From the ASCOM Telescope Chooser pull-down menu, choose "Orion IntelliScope Mounts."
5. Click on "Properties."
6. Indicate which of your computer's COM ports you will use to connect the IntelliScope object locator from the pull-down menu. The COM1 port is the default. If you have another accessory (printer, scanner, etc.) connected to the COM1 port, you will have to choose another COM port.
7. Check the box marked "Align Upon Connecting."
8. Enter the aperture and focal length of the IntelliScope you are using in the appropriate fields.
9. Make sure the box marked "Clock Driven" is unchecked.
10. Click "OK."
11. Click "OK" on the ASCOM Telescope Chooser.
To physically connect the IntelliScope object locator to your computer, you must have the PC Interface Cable (Orion #5222). The modular plug end of the cable goes into the object locator's RS-232 jack, and the other end connects to the serial cable interface (COM port) of your computer.
To use the IntelliScope system with Starry Night Pro:
1. Set up the telescope and object locator as you would normally do.
2. Make sure the PC interface cable is properly connected to the object locator and computer.
3. Press the object locator's POWER button, then press the ENTER button. The telescope does not need to be in any specific position at this point.
4. Open the Starry Night Pro program on your computer.
5. Click on the tab marked "Telescope" at the bottom of the vertical row of tabs on the left side of the main display screen.
6. Click "Connect" and follow the prompts:
* Set the telescope so that the tube is horizontal (estimating is OK); click "Continue."
* Set the telescope so that the tube is vertical (estimating is OK); click "Continue."
* Do a two-star alignment using the procedure and star list displayed.
The IntelliScope system is now connected and aligned to the Starry Night Pro software. The current position the telescope is pointed to will be indicated by a red crosshair on Starry Night Pro's sky map. We recommend clicking the box marked "Follow Scope" in the "Telescope" tab; this will center the Starry Night Pro star map on the current position of the telescope crosshairs.
Be aware of the time-out feature of the IntelliScope object locator. Press one of the arrow buttons periodically to avoid the auto-shutoff routine. Since you will not be actually handling the object locator, it will be easy to forget to do this. You will have to perform the alignment procedure again if the object locator does shut off.