Maybe the idea of a big-aperture telescope appeals to you, but the portability issue has kept you on the fence. Well you can hop off it now because we?ve got the perfect solution ? the "space-saving" Orion SkyQuest XX12i IntelliScopeŽ Truss Tube Dobsonian. It?s a deep-sky observer?s dream telescope, offering jumbo 12" (305mm) Pyrex parabolic optics of 1500mm focal length (f/4.9); a stylish, reduced-weight base outfitted with computerized IntelliScope object locating technology; and a sturdy, eight-truss tube design that disassembles in about a minute into compact, easily portable components. And at its price, the XX12i ranks as the #1 killer telescope deal of the year!
Finally, a deluxe, large-aperture Dobsonian that fits comfortably into a compact car for transport to your favorite observing site! Credit the XX12i?s traditional truss tube design, which utilizes eight aluminum trusses (four captive pairs) that attach and detach quickly with oversized hand knobs ? no tools required! This design provides a more rigid structural support than other designs in this category. And all assembly knobs are captive, so you won?t lose any in the dark! When removed, the trusses in each captive pair align in parallel, which saves space when transporting and storing them. Disassembly of the 56"-long optical tube yields two sections, the largest measuring just 26" in length.
The XX12i improves on the already stellar features and performance of our standard XT12 IntelliScope Dobsonian. The focuser is a dual-speed (11:1) 2" Crayford with 1.25" adapter, metal focus knobs, and adjustable drawtube tension to ensure excellent, non-slip motion for any size of eyepiece used. We outfitted the XX12i with larger, 8" altitude bearings for smoother tube motion. The side-reinforced base sports stylish cutouts that minimize weight without sacrificing stability. EbonyStar laminate glides on nonstick PTFE to give the azimuth motion the feel of silk. Fine features carried over from the XT12 include adjustable altitude tension, an open 9-point flotation primary mirror cell, and a "navigation knob" for easy slewing.
Although the primary mirror cell is extremely well ventilated, the Orion SkyQuest XX12i Intelliscope Truss Dobsonian comes with a Cooling Accelerator Fan, which attaches to the back of the cell and facilitates faster equilibration of the mirror to ambient temperature. The secondary mirror has a 70mm minor axis and is held in a four-vane spider with very thin (0.7mm thick) vanes to minimize diffraction effects.
The acclaimed IntelliScope Computerized Object Locator comes standard on the XX12i, allowing manual slewing to any of 14,000 celestial objects in just seconds, using its illuminated pushbutton keypad. It lets you spend your time viewing celestial objects instead of hunting for them. What?s more, with the XX12i?s Truss Dobsonian 305mm of light-grabbing aperture, your favorite "faint fuzzies" won?t look nearly so faint or fuzzy! The deep-sky views will simply dazzle you.
The XX12i Truss comes fully loaded with great accessories, including a 9x50 finder scope, aluminum telescope eyepiece rack, two telescope eyepieces: a low-power 35mm (43x) DeepView 2" and a high-power 10mm (150x) Sirius Plossl 1.25", dust caps for the top and bottom optical tube sections, and a "collimating cap" to insure optical alignment of the mirrors. A convenient carrying handle is provided for the base.
It?s the big Dobsonian you?ve dreamed of owning, and now you can take it with you wherever dark skies beckon! Get the practical and amazingly affordable Orion SkyQuest XX12i IntelliScope Truss Tube Dobsonian by Orion and hit the road to astronomical adventure.
Assembled weight (including accessories): 86.5 lbs. Assembled optical tube, 56"L x 14"W, 49.5 lbs. Bottom tube section, 26"L x 14"W, 34.3lbs; top tube section, 8"L x 14"W, 9.6 lbs. Truss poles (8), 22"L x 1"W. Total weight of 4 Truss pole pairs and captive assembly knobs: 5.6lbs. Base, 25"W x 30"H, 34lbs. 12V battery pack included (requires 8 D-cells: not included) to power Cooling Accelerator Fan.
Sky & Telescope ? July 2009
"I was struck by the attention to little details, all based on time-tested Dobsonian principles, that demonstrated that this scope was designed by someone who understood how it would be used in the field."
"If the SkyQuest XX12i IntelliScope were a car, it would be the model that dealers keep in the showroom to impress prospective buyers."
"The XX12i comes with the most effective altitude friction adjustment I?ve seen on a commercial Dob... The motions of the SkyQuest are among the best I?ve experienced..."
"If good optics in an easy-to-aim, well-built scope were the end of the story, the 12-inch SkyQuest would be a winner. But there?s much more."
"I had fun using the computerized locator. I really got a kick out of choosing objects at random just to see what would greet me in the eyepiece. It was fun ? and isn?t that what telescopes are all about?"
"Of the three commercial 12-inch Dobsonians I?ve used in recent months, the XX12i is the one I enjoyed the most."
"I think the SkyQuest XX12i IntelliScope Truss Tube Dobsonian is the ideal next scope for any observer who has learned his or her chops on an 8-inch or smaller instrument and is ready to move up to something bigger."
Astronomy Magazine ? August 2009
"...I swung the [XX12i] toward the Orion Nebula (M42), which lies in the Hunter?s sword. The view through the 35mm eyepiece was that evening?s "wow" moment. Faint tendrils of nebulosity filled the field. It was striking."
"Returning to the Trapezium with a 5mm eyepiece (300x), I noted that the image remained sharp and clear. Even boosting to a ridiculous magnification of 700x didn?t compromise the view, a testament to the XX12i?s optical excellence."
"I came away impressed with Orion?s XX12i. In it, intelligent design and high-quality components come together to create one of the finest instruments of its size sold today."
"If you?re a visual deep-sky observer like me and are looking for a telescope that will enthrall you for years, the XX12i should be on your short list of candidates."
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
Fainter deep sky
Best for imaging
Lunar & planetary
Finder scope lens diameter
Low thermal expansion glass
DeepView 35.0mm (2"), 10.0mm (1.25")
Magnification with included eyepieces
Highest theoretical magnification
2" dual-speed Crayford
Secondary mirror obstruction
Secondary mirror obstruction by diameter
Secondary mirror obstruction by area
Enhanced Aluminum & Silicon Dioxide
Sealed ball bearings
Electronic, via the hand controller
Length of optical tube
Weight, optical tube
Weight, fully assembled
Additional included accessories
Unique base design with side braces for stability, Cooling accelerator fan included, 2" dual-speed Crayford focuser w/ 1.25" adapter
In The Box
Orion SkyQuest XX12" f/4.9 Truss-Tube Dobsonian Reflector Telescope w/ parabolic primary optics
9-point flotation primary mirror cell with spring loaded thumbscrew collimation adjustments
70mm minor-axis secondary mirror on 4-vaned (0.7mm thick vanes) secondary holder
4 groups of two-pole rotatable truss assemblies with captive assembly knobs
Dual-Speed (11:1) 2" Crayford focuser w/ 1.25" telescope eyepiece adapter and adjustable focusing tension
Orion unique new base design with side braces for increased stability
Base outfitted with EbonyStar on nonstick PTFE azimuth bearings for optimized motion
Large 8" diameter ABS plastic altitude bearings with adjustable CorrecTension knobs
Orion IntelliScope Computerized Object Locator system
9-volt battery (for IntelliScope Object Locator)
Telescope eyepiece rack (holds one 2" eyepiece and three 1.25" eyepieces)
9x50 finder scope
35mm DeepView 2" eyepiece
10mm Sirius Plossl telescope eyepiece
Cooling Accelerator Fan
12V battery pack for Cooling Fan (requires 8 D cell batteries: not included)
Dust covers for top and bottom tube sections
Base assembly hardware
Orion 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: $35.00
3 Day Air Delivery: $395.00
2 Day Delivery: $395.00
Next Day Delivery: $537.00
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 to Find Deep-sky Objects: 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-deg - 7-deg, so you should choose a star that is no more than 7-deg 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.
How do I balance my SkyQuest Classic Tube?
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-deg (upside-down and reversed left-to-right). This is normal for astronomical telescopes. The finder scope view will also be rotated 180-deg, unless you have a correct-image finder. If your finder scope view is rotated 180-deg, 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-deg 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.