Thanks to its sturdy altazimuth mount and quality refractive optics, the Orion Observer 70mm refractor telescope works well for both daytime terrestrial viewing and nighttime astronomical use. The included altazimuth mount offers intuitive up/down (altitude) and left/right (azimuth) motion to make maneuvering the telescope easy. Whether you're scanning a scenic landscape or surveying the Milky Way for star clusters, this telescope will provide a pleasant experience.
The Observer 70mm Altazimuth Refractor Telescope is well suited to beginning astronomers thanks to its versatility and simple, easy-to-use design. It is a very lightweight and compact telescope, weighing just 6.5 lbs. once assembled, so it's easy to carry to any observing location, be it out on the lawn or an hour's drive into the hills.
Its glossy black refractor telescope optical tube is made of seamless aluminum and outfitted with a smooth-action rack-and-pinion focuser which accepts 1.25" accessories and eyepieces. Housed inside the telescope tube is a multi-coated, achromatic glass objective lens that is 70mm in diameter, with a focal length of 700mm (f/10). This lens takes in 36% more light than a 60mm lens, meaning you'll be able to see more detail on both celestial and terrestrial objects. Compared to a 60mm refractor, the Orion Observer 70mm and its larger optics will reward you with brighter images and, for astronomy, a larger repertoire of objects to see. You'll enjoy outstanding looks at the Moon's cratered surface, Jupiter's cloud bands and moons, Saturn and its rings, the majestic Orion Nebula, and the mind-boggling Andromeda Galaxy, to name just a few of the treasures you can see. A dew and glare shield on the objective end (or front of the telescope) helps prevent dew from forming on the optical lens and also helps block unwanted stray light.
The specially engineered altazimuth mount provides much greater stability than standard "off the shelf" altazimuth mounts found in many department stores. It has an altitude micro-motion control to allow very fine aiming adjustments. The refractor telescope tube and mount are supported on a sturdy aluminum tripod that adjusts to comfortable heights for the whole family to use.
The Observer 70mm telescope comes with everything you need to start observing the night sky right away. Standard accessories include an Orion EZ Finder II reflex sight which helps you easily aim the telescope, a 90° mirror star diagonal that provides bright nighttime views at a comfortable angle, two 1.25" telescope eyepieces, and an accessory tray for the tripod so you can keep your eyepieces ready for action. The included 25mm eyepiece provides 28x power magnification, while the higher power 10mm eyepiece boost the magnification up to a substantial 70x power for up close views.
To make the Orion Observer 70 perform as a high-quality daytime telescope to scan scenery, wildlife and more, an optional 45° correct-image diagonal can be substituted for the 90° diagonal. This optional accessory will make the Observer 70 yield a view with correct, non-reversed daytime orientation. Correct-image 45° diagonals are sold separately by Orion.
The Orion Observer 70 Altazimuth refractor is a telescope that will keep any observer entranced for years. Get in on the fun today!
Sky & Telescope Magazine - December 2005
"The best refractor in our roundup."
"The refractor with the best optics was the Orion Observer 70mm."
"The one exception [to scopes with jiggly tripods] was the Orion Observer refractor, which settled down in about half the time of the others, resulting in a much more enjoyable viewing experience."
"If you'll be doing a fair amount of daytime viewing, the Orion Observer 70mm refractor is worth considering since it provides a right-side-up (though mirror-reversed) view."
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.
Visit our product support section for instruction manuals and more
Best for viewing
Lunar & planetary
Best for imaging
Lunar & planetary
Explorer II 25.0mm,10.0mm (1.25")
Magnification with included eyepieces
Highest theoretical magnification
EZ Finder II
1.25" 90° Mirror Star
Length of optical tube
Weight, fully assembled
Additional included accessories
Altitude fine adjustment
In The Box
Orion 70mm f/10.0 refractor telescope optical tube assembly
25mm Orion Explorer II telescope eyepiece (1.25")
10mm Orion Explorer II telescope eyepiece (1.25")
90º mirror star diagonal
Altazimuth yoke mount
EZ Finder II finder scope
Orion finder scope bracket
Tripod accessory tray
Altitude micro-motion control rod and thumbwheel
Tripod attachment screws
Accessory tray attachment wing screws
Leg lock knobs
Starry Night special edition software
How do I align the EZ Finder II and EZ finder Deluxe?
When the EZ Finder is properly aligned with the telescope, an object that is centered on the EZ Finder red dot should also appear in the center of the field of view of the telescope’s eyepiece. Alignment of the EZ Finder is easiest during daylight, before observing at night. Aim the telescope at a distant object such as a telephone pole or roof chimney and center it in the telescope’s eyepiece. The object should be at least 1/4 mile away. Now, with the EZ Finder turned on, look though the EZ Finder. The object should appear in the field of view. Without moving the main telescope, use the EZ Finder’s azimuth (left/right) and altitude (up/down) adjustment to position the red dot on the object in the eyepiece. When the red dot is centered on the distant object, check to make sure that the object is still centered in the telescope’s field of view. If not, re-center it and adjust the EZ Finder’s alignment again. When the object is centered in the eyepiece and on the EZ Finder’s red dot, the EZ Finder is properly aligned with the telescope. Once aligned, EZ Finder will usually hold its alignment even after being removed and remounted. Otherwise, only minimal realignment will be needed.
How do I replace the EZ finder II battery?
Should the battery ever die, replacement 3-volt lithium batteries are available from Orion and many retail outlets. The finder uses a CR-2032 battery. Remove the old battery from the EZ finder II by inserting a small flat-head screwdriver into the slot on the battery casing and gently prying open the case. Then carefully pull back on the retaining clip and remove the old battery. Do not over-bend the retaining clip. Then slide the new battery under the battery lead with the positive (+) end facing down and replace the battery casing.
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 Observer 70mm Altazimuth Refractor Telescope, which has a focal length of 700mm, used in combination with the supplied 25mm eyepiece, yields a power of: 700 ÷ 25 = 28x.
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. 140x for the Orion Observer 70mm Altazimuth Refractor Telescope). 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. See our Learning Center articles: About General Astronomy
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.
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.
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. See this link to the Orion Star Chart on our website. 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. For more details, see our learning center article Observing Deep Sky Objects
Observing Hint: Always use your lowest powered eyepiece in your telescope when starhopping . This will give you the widest possible field of view.
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
How do I clean any of the optical lenses?
Any quality optical lens cleaning tissue and optical lens cleaning fluid specifically designed for multi-coated optics can be used to clean the exposed lenses of your eyepieces or finder scope. Never use regular glass cleaner or cleaning fluid designed for eyeglasses. Before cleaning with fluid and tissue, blow any loose particles off the lens with a blower bulb or compressed air. Then apply some cleaning fluid to a tissue, never directly on the optics. Wipe the lens gently in a circular motion, then remove any excess fluid with a fresh lens tissue. Oily finger-prints and smudges may be removed using this method. Use caution; rubbing too hard may scratch the lens. On larger lenses, clean only a small area at a time, using a fresh lens tissue on each area. Never reuse tissues.
Is there an image quality difference between a short-tube and long-tube?
Short refractors have more visible chromatic aberration than long refractors. You’re likely to see purple or orange halos around bright planets and the lunar limb. With short reflectors, “coma” comes into play: stars appear like “commas” or “seagulls” near the edge of the eyepiece field. For most people, a little color fringing or coma is no big deal. These aberrations are less noticeable at low magnifications, which is one reason not to push the power higher than about 100x in most short-tube telescopes. High-end short-tubes made with exotic glasses or with corrector lenses can handle higher power. For more detailed information on this topic see our Learning Center article: Short Tube vs Long Tube- What’s the Difference