Orion 120ST EQ Telescope User Manual
Contents
1. As before connect the T ring to your camera Before connect ing the camera adapter to the T ring an eyepiece must be inserted and locked into the body of the camera adapter Start by using a medium low power eyepiece about 25mm you can increase the magnification later with a higher power eye piece Then connect the entire camera adapter with eyepiece inside to the T ring Insert the whole system into the tele scope s focuser drawtube and secure firmly with the thumbscrew Aim the telescope at the planet or Moon you wish to shoot The image will be highly magnified so you may need to use the finder scope to center it within the camera s viewfinder Turn the motor drive on Adjust the telescope s focuser so that the image appears sharp in the camera s viewfinder The camera s shutter is now ready to be opened A remote shutter release must be used or the image will be blurred beyond recognition Try expo sure times between 1 and 10 seconds depending upon the brightness of the planet to be photographed and the ISO of the film being used Piggybacking Photography The Moon and planets are interesting targets for the budding astrophotographer but what next Literally thousands of deep sky objects can be captured on film with a type of astrophotography called piggybacking The basic idea is that a camera with its own camera lens attached rides on top of the main telescope The telescope and camera both mov2. longitude value is less than the standard time merid ian value you are 5 east of the closest time meridian Take your calculated difference from the closest standard time meridian and rotate the date circle so that the meridian offset scale line that corresponds to your calculated difference lines up with the engraved time meridian indicator mark on the polar finder housing Each line of the meridian offset scale represents 5 of longitude Lines to the left of the 0 on the meridian offset scale indicate east of the closest standard time meridian while lines to the right of the O indicate west of the closest standard time meridian Continuing with the prior example of observing in Las Vegas you would rotate the date circle so that the first line to the left of the 0 on the meridian offset scale lines up with the time meridian indicator mark Make sure that the 0 mark on the R A setting circle lines up with the pointed indicator cast into the mount and that the large thumbscrew just above it is tightened Now rotate the mount about the R A axis of the mount until the line on the R A setting circle that corresponds to your current local time lines up with the line on the date circle that indicates the cur rent date If you are on daylight savings time subtract one hour from your current local time For example if it was November 1 at 9 PM you would rotate the telescope in R A until the line above the 21
3. cator mark Polar scope Polar scope A alignment housing thumbscrew 3 Polar axis Figure 4 The polar axis finder scope installed in the right ascension R A axis of the mount BN Byrd fe pea e Figure 5 Proper operation of the equatorial mount requires that the telescope tube be balanced on both the R A and Dec axes a With the R A lock knob released slide the counterweight along the counterweight shaft until it just counterbalances the tube b When you let go with both hands the tube should not drift up or down c With the Dec lock knob released loosen the tube ring lock clamps a few turns and slide the telescope forward or back in the tube rings d When the tube is balanced about the Dec axis it will not move when you let 3 Balancing the Telescope To ensure smooth movement of the telescope on both axes of the equatorial mount it is imperative that the optical tube is properly balanced We will first balance the telescope with respect to the R A axis then the Dec axis 1 Keeping one hand on the telescope optical tube loosen the R A lock lever Make sure the Dec lock lever is locked for now The telescope should now be able to rotate freely about the R A axis Rotate it until the counterweight shaft is parallel to the ground i e horizontal Now loosen the counterweight lock knobs and slide the weights along the shaft until they exactly counterbalance the telescope Figure 5a
4. on the R A setting circle lines up with the long line between the 10 and 11 on the date cir cle Finally look through the polar alignment finder scope while shining a red flashlight at an angle down the front opening of the R A axis and center Polaris in the small circle Do this by rotating the tripod left or right and adjusting the tilt of the R A axis up or down with the latitude adjustment T bolts When you are close you can use the azimuth fine adjustment knobs Figure 8 for final positioning To do this you will first need to loosen the big tripod attachment knob directly underneath the base of the equatorial mount The fine adjustment knobs work by loosening one and then tightening the other When done retighten the tripod attachment knob to firmly secure the mount and tripod Once Polaris is centered in the small circle you are done The telescope is now accurately polar aligned and can be used for advanced observational applications such as astropho tography or precise use of the manual setting circles As mentioned before only move the telescope along the R A and Dec axes if you move the tripod or change the tilt of the equatorial mount you will need to polar align again Remember accurate polar alignment is not needed for casual visual observing Most of the time approximate polar alignment as outlined previously will suffice Tracking Celestial Objects When you observe a celestial object
5. Polaris will be centered is located straight down from the intersection of the crosshairs Retighten the thumbscrews The polar axis finder scope is now properly set in its initial position Next we must align it so that it is exactly parallel to the mount s R A axis 6 Look through the polar finder at a distant object during the day and center it on the crosshairs You may need to adjust the latitude adjustment T bolts and the tripod position to do this 7 Rotate the mount 180 about the R A axis Again it may be convenient to remove the counterweights and optical tube first 8 Look through the polar finder again Is the object being viewed still centered on the crosshairs If it is then no further adjustment is necessary If not then look through the polar finder while rotating the mount about the R A axis You will notice that the object you have previously centered moves in a circular path Use the three thumb screws on the housing to redirect the crosshairs of the polar finder to the apparent center of this circular path Repeat this procedure until the position that the crosshairs point to does not rotate off center when the mount is rotated in R A Once this is accomplished retighten the thumbscrews The polar axis finder scope is now ready to be used When not in use replace the plastic protective cover to prevent the polar finder from getting bumped which could knock it out of align ment Using the Polar A
6. center of the crosshairs Any drifting along the Dec axis is a result of improper polar alignment so if the guide star drifts greatly in Dec the mount may need to be polar aligned more accurately When the exposure is complete unlock the shutter release cable and close the camera s shutter Astrophotography can be enjoyable and rewarding as well as frustrating and time consuming Start slowly and consult out side resources such as books and magazines for more details about astrophotography Remember have fun 8 Terrestrial Viewing The AstroView 120ST Refractor may also be used for long dis tance viewing over land For this application we recommend substitution of an Orion 45 Correct lmage Diagonal for the 90 star diagonal that comes standard with the telescope The cor rect image diagonal will yield an upright nonreversed image and also provides a more comfortable viewing angle since the tele scope will be aimed more horizontally for terrestrial subjects For terrestrial viewing it s best to stick with low powers of 50x or less At higher powers the image loses sharpness and clar ity That s because when the scope is pointed near the horizon it is peering through the thickest and most turbulent part of the Earth s atmosphere Remember to aim well clear of the Sun unless the front of the telescope is fitted with a professionally made solar filter and the finder scope is covered with foil or some other comp
7. should again be horizontal Then you simply rotate the scope on the Dec axis until it points in the south direction To point the telescope to the east or west or in other directions you rotate the telescope on its R A and Dec axes Depending on the altitude of the object you want to observe the counterweight shaft will be oriented somewhere between vertical and horizon tal Figure 9 illustrates how the telescope will look when pointed at the four cardinal directions north south east and west The key things to remember when pointing the telescope are that a you only move it in R A and Dec not in azimuth or latitude altitude and b the counterweight and shaft will not always appear as it does in Figure 1 In fact it almost never will 6 Using Your Telescope Astronomical Observing Choosing an Observing Site When selecting a location for observing get as far away as possible from direct artificial light such as streetlights porch lights and automobile headlights The glare from these lights will greatly impair your dark adapted night vision Set up on a grass or dirt surface not asphalt because asphalt radiates more heat Heat disturbs the surrounding air and degrades the images seen through the telescope Avoid viewing over rooftops and chimneys as they often have warm air currents rising from them Similarly avoid observing from indoors through an open or closed window because the tempera ture differen
8. A setting circles for finding objects the thumbscrew is only needed for polar alignment using the polar axis finder scope Finding Objects With the Setting Circles Now that both setting circles are calibrated look up in a star atlas the coordinates of an object you wish to view 1 Loosen the Dec lock lever and rotate the telescope until the Dec value from the star atlas matches the reading on the Dec setting circle If the telescope is being aimed toward the south and the Dec setting circle pointer pass es the 0 indicator the value on the Dec setting circle becomes a negative number Retighten the lock lever 2 Loosen the R A lock lever and rotate the telescope until the R A value from the star atlas matches the reading on the R A setting circle Retighten the lock lever Most setting circles are not accurate enough to put an object dead center in your finder scope s field of view but they ll get you close assuming the equatorial mount is accurately polar aligned The R A setting circle should be recalibrated every time you wish to locate a new object Do so by calibrating the setting circle for the centered object before moving on to the next one Confused About Pointing the Telescope Beginners occasionally experience some confusion about how to point the telescope overhead or in other directions In Figure 1 the telescope is pointed north as it would be during polar alignment The counterweight shaft is orient
9. That s the point at which the shaft remains horizontal even when you let go with both hands 5b Retighten the counterweight lock knobs The telescope is now balanced on the R A axis To balance the telescope on the Dec axis first tighten the R A lock lever with the counterweight shaft still in the horizontal position With one hand on the telescope optical tube loosen the Dec lock lever The telescope should now be able to rotate freely about the Dec axis Loosen the tube ring clamps a few turns until you can slide the telescope tube forward and back inside the rings this can be aided by using a slight twisting motion on the optical tube while you push or pull on it 5c Position the telescope in the mounting rings so it remains horizontal when you carefully let go with both hands This is the balance point for the optical tube with respect to the Dec axis 5d Retighten the tube ring clamps The telescope is now balanced on both axes Now when you loosen the lock lever on one or both axes and manually point the telescope it should move without resistance and should not drift from where you point it 4 Aligning the Finder Scope A finder scope has a wide field of view to facilitate the location of objects for subsequent viewing through the main tele scope which has a much narrower field of view The finder scope and the main telescope must be aligned so they point to exactly the same spot in
10. distance away 3 Loosen the Dec lock lever and rotate the telescope opti cal tube until it is parallel with the R A axis The pointer on the Dec setting circle should read 90 Retighten the Dec lock lever 4 Move the tripod so the telescope tube and R A axis points roughly at Polaris If you cannot see Polaris direct ly from your observing site consult a compass and rotate the tripod so the telescope points north There is a label bearing a large N at the base of the equatorial mount Figure 8 It should be facing north The equatorial mount is now approximately polar aligned for casual observing More precise polar alignment is required for astrophotography and for use of the manual setting circles Note From this point on in your observing session you should not make any further adjustments to the latitude of the mount nor should you move the tripod Doing so will undo the polar alignment The telescope should be moved only about its R A and Dec axes The Polar Axis Finder Scope A nice feature of the AstroView 120ST is the polar axis finder scope housed inside the R A axis of the equatorial mount see Figure 4 When properly aligned and used it makes accurate polar alignment quick and easy to do Alignment of the polar finder need only be done once unless it gets bumped or otherwise shifts its position Remove the round cover cap from the front opening in the R A axis of the mount see Figure 6 Look
11. mount of the AstroView 120ST EQ Little Dipper in Ursa Minor Big Dipper in Ursa Major Polaris pointe Cassiopeia stars Figure 7 To find Polaris in the night sky look north and find the Big Dipper Extend an imaginary line from the two Pointer Stars in the bowl of the Big Dipper Go about five times the distance between those stars and you ll reach Polaris which lies within 1 of the north celestial pole NCP To find Polaris in the sky look north and locate the pattern of the Big Dipper Figure 7 The two stars at the end of the bowl of the Big Dipper point right to Polaris Observers in the Southern Hemisphere aren t so fortunate to have a bright star so near the south celestial pole SCP The star Sigma Octantis lies about 1 from the SCP but it is barely visible with the naked eye magnitude 5 5 For general visual observation an approximate polar align ment is sufficient 1 Level the equatorial mount by adjusting the length of the three tripod legs 2 Loosen one of the latitude adjusting T bolts and tighten the other to tilt the mount until the pointer on the latitude scale is set at the latitude of your observing site If you don t know your latitude consult a geographical atlas to find it For example if your latitude is 35 North set the pointer to 35 The latitude setting should not have to be adjusted again unless you move to a different viewing location some
12. objective lens cell The finder scope s focus should not need to be adjusted again 5 Setting Up and Using the Equatorial Mount When you look at the night sky you no doubt have noticed that the stars appear to move slowly from east to west over time That apparent motion is caused by the Earth s rotation from west to east An equatorial mount Figure 6 is designed to compensate for that motion allowing you to easily track the movement of astronomical objects thereby keeping them from drifting out of the telescope s field of view while you re observing This is accomplished by slowly rotating the telescope on its right ascension R A axis using only the R A slow motion cable But first the R A axis of the mount must be aligned with the Earth s rotational polar axis a process called polar alignment Polar Alignment For Northern Hemisphere observers approximate polar alignment is achieved by pointing the mount s R A axis at the North Star or Polaris It lies within 1 of the north celestial pole NCP which is an extension of the Earth s rotational axis out into space Stars in the Northern Hemisphere appear to revolve around Polaris Declination Setting Circle Front opening in R A axis Declination lock lever Right Ascension lock lever Right Ascension Setting Circle Ta Polar axis finder scope Latitude scale Latitude adjusting T bolts Figure 6 The equatorial
13. the sky Alignment is easiest to do in daylight hours First insert the lowest power 25mm eyepiece into the star diagonal Then loosen the R A and Dec lock levers so the telescope can be moved freely Point the main 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 Move the telescope so the target object appears in the very center of the field of view when you look into the eyepiece Now tighten the R A and Dec lock levers Use the slow motion control knobs to re center the object in the field of view if it moved off center when you tightened the lock levers Now look through the finder scope Is the object centered in the finder scope s field of view i e on the crosshairs If not hopefully it will be visible somewhere in the field of view so that only fine adjustment of the finder scope alignment screws will be needed to center it on the crosshairs Otherwise you ll have to make coarser adjustments to the two black nylon alignment thumbscrews to redirect the aim of the finder scope Note that the image seen through the finder scope appears upside down This is normal for astronomical finder scopes Once the target object is centered on the crosshairs of the finder scope look again in the main telescope s eyepiece and see if it is still centered there as well If it isn t repeat the entire process making sure not to move the main telescope while a
14. At low pow ers long focal lengths 2 eyepieces can give a wider field of view than standard 1 25 eyepieces This is especially desir able for observing deep sky objects as many of them appear quite big but faint If you want to use 2 eyepieces such as the Orion Optiluxe 2 eyepieces we recommend that you also purchase a 2 star diagonal for refractors this will provide for a comfortable viewing angle To use 2 eyepieces simply loosen the two large thumbscrews on the focuser drawtube that are just in front of the thumbscrew that holds the provided 1 25 star diagonal in place Once these large thumbscrews are loosened the entire back end of the focuser including any 1 25 diagonal and eyepiece that may be attached comes off exposing the 2 diameter focuser drawtube Now insert your 2 star diagonal into the drawtube and secure with the two large thumbscrews Insert a 2 eyepiece into the 2 diagonal secure it in place with the thumbscrew on the diagonal and you re ready to observe Let Your Eyes Dark Adapt Don t 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 of their full dark adapted sensitivity As your eyes become dark adapt ed more stars will glimmer into view and you ll be able to see fainter details in objects you view in your te
15. INSTRUCTION MANUAL Orion AstroView 120ST EQ 9005 Equatorial Refracting Telescope Customer Support 800 676 1343 _ ORIONI E mail support telescope com TELESCOPES amp BINOCULARS Corporate Offices 831 763 7000 Providing Exceptional Consumer Optical Products Since 1975 89 Hangar Way Watsonville CA 95076 IN 155 Rev B 02 09 Tube rings Objective lens cell Dew cap lens shade Declination lock lever Finder scope Finder bracket Large counterweight Small counterweight Focus knob Eyepiece Star diagonal SN Counterweight lock knobs Counterweight shaft Right Ascension slow motion control Declination slow motion control Right Ascension lock lever _______ Polar axis finder scope Toe saver 4 Latitude adjustment T bolts Tripod leg S i Accessory tray attachment point t AA Accessory tray bracket Accessory tray Leg lock knob Figure 1 The AstroView 120ST EQ Refractor Congratulations on your purchase of a quality Orion telescope Your new AstroView 120ST EQ Refractor is designed for high resolution viewing of astronomical objects With its precision optics and equatorial mount you ll be able to locate and enjoy hundreds of fascinating celestial denizens including the plan ets Moon and a variety of deep sky galaxies nebulas and star clusters If you have never owned a telescope we are pleased to welcome you to a
16. an image that is much better color corrected than a non achro matic one element objective lens Even with the achromatic lens design however the AstroView 120ST will suffer a bit from chromatic abberation due to its large aperture and short focal length This will be noticeable to some degree on extremely bright objects such as the brightest stars in the sky What you will notice is that the object when focused has a slight purple halo around it This will not present a problem for most observers as the eye readily adapts to the view and is still able to distinguish fine details Chromatic abberation will never inhibit deep sky observing as deep sky objects are too faint to cause any noticeable color distortion How to Find Interesting Celestial Objects To locate 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 unless or course you look up its celestial coordinates and use the telescope s setting circles Even then it would be good to know in advance whether that constellation will be above the horizon at the time you plan to observe A simple planisphere or star wheel can be a valuable tool both for learning the constellations and for determining which ones are visible on a given night at a given time A good star chart or atlas will com
17. arts List 25mm 40x Plossl eyepiece 1 25 Qty Description 10mm 100x Pl ssl eyepiece 1 25 A a se em telescope only with adult supervision 6x30 achromatic crosshair finder scope 1 Optical tube assembly 1 G t torial mount Seer erman type equa ga Assembly Tools 2 wrenches Phillips screwdriver 1 Large counterweight flat head screwdriver key 1 Small counterweight 1 Counterweight shaft 3 Tripod Legs with mounting hardware 1 Accessory tray with mounting hardware 1 Accessory tray bracket WARNING Never look directly at the Sun 2 Slow motion control cables through your telescope or its finder scope 1 Pol is find even for an instant without a professionally Sennen eee made solar filter that completely covers the front 1 Plastic cover for polar axis finder scope of the instrument or permanent eye damage 2 Optical tube mounting rings could result Young children should use this 1 1 Finder scope bracket with O ring 2 Assembly Carefully open all of the boxes in the shipping container Make sure all the parts listed in Section 1 are present Save the boxes and packaging material In the unlikely event that you need to return the telescope you must use the original packag ing Assembling the telescope for the first time should take about 30 minutes No tools are needed other than the ones pro vided All bolts should be tightened securely to eliminate flexing and wobbling but be careful not to o
18. ce between the indoor and outdoor air will cause image blurring and distortion If at all possible escape the light polluted city sky and head for darker country skies You ll be amazed at how many more stars and deep sky objects are visible in a dark sky 11 Cooling the Telescope All optical instruments need time to reach thermal equilibri um 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 tele scope as cold as possible If it has to adjust to more than a 40 temperature change allow at least one hour Aiming the Telescope To view an object in the main telescope first loosen both the R A and Dec lock levers Aim the telescope at the object you wish to observe by eyeballing along the length of the telescope tube or use the setting circles to dial in the object s coordinates Then look through the aligned finder scope and move the telescope tube until the object is generally centered on the finders crosshairs Retighten the R A and Dec lock levers Then accurately center the object on the finder s crosshairs using the R A and Dec slow motion controls The object should now be visible in the main telescope with a low power long focal length eyepiece If neces sary use the R A and Dec slow motion controls to
19. djusting the alignment of the finder scope When the target object is centered on the crosshairs of the finder scope and in the telescope s eyepiece the finder scope is now aligned and ready to be used for an observing session The finder scope and bracket can be removed from the dovetail for storage and then reinstalled without significantly changing the finder scope s alignment The finder scope alignment should be checked before every observing session This can easily be done at night before viewing through the telescope Choose any bright star or planet center the object in the telescope eyepiece and then adjust the finder scope s alignment screws until the star or planet is also centered on the finder s crosshairs The finder scope is an invaluable tool for finding objects in the night sky its usage for this purpose will be discussed later in detail If when looking through the finder scope you notice that the images appear somewhat out of focus you will need to refo cus the finder scope for your eyes First loosen the lock ring located behind the objective lens cell on the body of the finder scope see Figure 3 Back the lock ring off by a few turns for now Refocus the finder scope on a distant object by threading the objective lens cell in or out of the finder scope body Precise focusing will be achieved by focusing the finder scope on a bright star Once the image appears sharp retighten the lock ring behind the
20. e in very handy for helping find objects among the dizzying multitude of stars overhead Except for the Moon and the brighter planets it s pretty time consuming and frustrating to hunt for objects randomly without knowing where to look You should have specific tar gets in mind before you begin observing Start with a basic star atlas one that shows stars no fainter than 5th or 6th magnitude In addition to stars the atlas will show the positions of a number of interesting deep sky objects with different symbols representing the different types of objects such as galaxies open star clusters globular clus ters diffuse nebulas and planetary nebulas So for example your atlas might show a globular cluster sitting just above the lid of the Teapot pattern of stars in Sagittarius You then know to point your telescope in that direction to home in on the cluster which happens to be 6 9 magnitude Messier 28 M28 You can see a great number and variety of astronomical objects with your AstroView 120ST including A The Moon With its rocky cratered surface the Moon is one of the easi est and most interesting targets to view with your telescope The best time to observe our only natural satellite is during a partial phase that is when the Moon is NOT full During par tial phases shadows on the surface reveal more detail especially right along the border between the dark and light portions of the disk called the termina
21. e with the rotation of the Earth when the mount is polar aligned and the motor drive is engaged This allows for a long exposure through the camera without hav ing the object or background stars blurred In addition to the motor drive dual axis an illuminated reticle eyepiece is also needed The T ring and camera adapter are not needed since the camera is exposing through its own lens Any camera lens with a focal length between 35mm and 400mm is appropriate On top of one of the tube rings is a piggyback camera adapter This is the black knob with the threaded shaft protruding through it The tube ring with the piggyback adapter should be closest to the objective end of the telescope Remove the tube rings from the equatorial mount and swap their positions if necessary Now connect the camera to the piggyback adapter There should be a 1 4 20 mounting hole in the bottom of the camera s body Thread the protruding shaft of the piggyback adapter into the 1 4 20 mounting hole in the camera a few turns Position the camera so it is parallel with the telescope tube and turn the knurled black knob of the piggyback adapter counter clockwise until the camera is locked into position Aim the telescope at a deep sky object It should be a fairly large deep sky object as the camera lens will likely have a wide field of view Check to make sure that the object is also centered in the camera s viewfinder Turn the motor drive on Now look into t
22. ed down ward But it will not look like that when the telescope is pointed in other directions Let s say you want to view an object that is directly overhead at the zenith How do you do it One thing you DO NOT do is make any adjustment to the latitude adjustment T bolts That will spoil the mount s polar alignment Remember once the mount is polar aligned the telescope should be moved only on the R A and Dec axes To point the scope overhead first loosen the R A lock lever and rotate the telescope on the R A axis until the counter Figure 9 This illustration shows the telescope pointed in the four cardinal directions a north b south c east d west Note that the tripod and mount have not been moved only the telescope tube has been moved on the R A and Dec axes weight shaft is horizontal parallel to the ground Then loosen the Dec lock lever and rotate the telescope until it is pointing straight overhead The counterweight shaft is still horizontal Then retighten both lock levers What if you need to aim the telescope directly north but at an object that is nearer to the horizon than Polaris You can t do it with the counterweight down as pictured in Figure 1 Again you have to rotate the scope in R A so that the counterweight shaft is positioned horizontally Then rotate the scope in Dec so it points to where you want it near the horizon To point the telescope directly south the counterweight shaft
23. elescope Especially important for observing faint objects is good transparency air free of moisture smoke and dust All tend to scatter light which reduces an object s brightness Transparency is judged by the magnitude of the faintest stars you can see with the unaided eye 6th magnitude or fainter is desirable Note About Chromatic Abberation Chromatic abberation literally means color distortion Whenever light passes through one material to another light of different wavelengths color is bent by different amounts This is a prob lem that plagues refractor type telescopes since light passes through both air and glass to form an image Most astronomical objects emit a spectrum comprised of many different wave lengths of light so each wavelength will be bent by a slightly different amount when passing through a lens This results in each color of light reaching precise focus at a slightly different point which will provide unacceptable images Achromatic refractors like the AstroView 120ST are designed to minimize chromatic abberation to acceptable levels The objective lens is actually comprised of two individual lenses called elements made of different materials which bend light in slightly different ways By precisely spacing and shaping the elements the chromatic abberation incurred when light passes through air and the first glass element is reduced by the way the second element bends the light The result is
24. fy stars to appear as 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 favor ites Defocusing the image of a star slightly can help bring out its color E Deep Sky Objects Under dark skies you can observe a wealth of fascinating deep sky objects including gaseous nebulas open and glob ular star clusters and different types of galaxies 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 subjects to appear like the photographs you see in books and magazines most will look like dim gray smudges Our eyes are not sensitive enough to see color in such faint objects But as you become more experienced and your observing 14 skills get sharper you will be able to discern more subtle details Remember that the higher the magnification you use the dim mer the image will appear So stick with low power when observing deep sky objects because they re already very faint Consult a star atlas or observing guide for information on find ing and identifying deep sky objects A good source to start with is the Orion DeepMap 600 7 Astrophotography Several different types of astrophot
25. g positions of its four largest moons lo 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 see ing is necessary for a good view You might 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 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 D Stars Stars will appear like twinkling points of light in the telescope Even powerful telescopes cannot magni
26. h position that is cast into the mount located directly below the large thumbscrew see Figure 3 Retighten the thumbscrew 2 Rotate the date circle until the 0 line on the meridian offset scale lines up with the time meridian indicator mark The meridian offset scale is printed on the inner circumfer ence of the date circle and is labeled E20 to W20 The time meridian indicator mark is an engraved line on the exterior of the polar finder s housing It is on the ring of the housing that is closest to the date circle 3 The R A setting circle is labeled in hours from 0 to 23 military time For Northern Hemisphere observers refer to the top numbers on the setting circle Each small line represents 10 minutes of R A The date circle is labeled from 1 to 12 with each number representing a month of the year 1 is January 2 is February etc Each small line represents a two day increment 4 Loosen the R A lock lever and rotate the mount about the R A axis until the March 1 indicating mark the long line between the 2 and the 3 on the date circle lines up with the 4 PM mark the long line above the 16 on the R A setting circle You may find it convenient to remove both the counterweights and the telescope optical tube to do this 5 Now loosen the three thumbscrews on the polar finder housing and rotate the polar finder so the small circle where
27. he telescope s eyepiece and center the brightest star within the field of view Remove the eyepiece and insert the illuminated reticle eyepiece into the telescope s star diagonal Turn the eyepiece s illuminator on dimly Recenter the bright star guide star on the crosshairs of the reticle eyepiece Check again to make sure that the object to be photographed is still centered within the camera s field of view If it is not recenter it either by repositioning the camera on the piggyback adapter or by moving the main telescope If you move the main telescope then you will need to recenter another guide star on the illumi nated eyepiece s crosshairs Once the object is centered in the camera and a guide star is centered in the reticle eyepiece you re ready to shoot Deep sky objects are quite faint and typically require expo sures on the order of 10 minutes To hold the camera s shutter open this long you will need a locking shutter release cable Set the camera s shutter to the B bulb setting Depress the locking shutter release cable and lock it You are now expos ing your first deep sky object While exposing through the camera lens you will need to monitor the accuracy of the mount s tracking by looking through the illuminated reticle eyepiece in the main telescope If the guide star drifts from its initial position then use the hand con troller of the motor drive to move the guide star back to the
28. his First remove the screw using the supplied screw driver then line up one of the ends of the bracket with the attachment point and reinstall the screw Make sure the smooth side of the accessory tray bracket faces up 4 Now with the accessory tray bracket attached spread the tripod legs apart as far as they will go until the bracket is taut Attach the accessory tray to the brackets with the three wingnut head screws already installed in the tray Push the screws up through the holes in the bracket then thread them into the holes in the tray 5 Next tighten the wingnuts at the top of the tripod legs so the legs are securely fastened to the equatorial mount Use the larger wrench and your fingers to do this 6 Orient the equatorial mount as it appears in Figure 1 ata latitude of about 40 i e so the pointer next to the latitude scale located directly above the Orion logo on one side of the mount is pointing to the line at 40 To do this loosen one of the latitude adjusting T bolts and then tighten the other latitude adjusting T bolt until the pointer and the 40 Figure 2 To adjust the latitude angle of the equatorial mount loosen one of the two latitude adjustment T bolts then tighten the other line up Figure 2 The declination Dec and right ascen sion R A axes many need re positioning rotation as well Be sure to loosen the RA and Dec lock levers before doing this Retighten them once the eq
29. lescope To see what you re doing in the darkness use a red filtered flash light 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 such as the Orion RedBeam LED flashlight or you can cover the front of a regular incandescent flashlight with red cellophane or paper Beware too that nearby porch and street lights and car headlights will ruin your night vision Seeing and Transparency Atmospheric conditions vary significantly from night to night Seeing refers to the steadiness of the Earth s atmosphere at a given time In conditions of poor seeing atmospheric turbu 12 lence causes objects viewed through the telescope to boil If the stars are twinkling noticeably when you look up at the sky with just your eyes the seeing is bad and you will be limited to viewing with low powers bad seeing affects images at high powers more severely Planetary observing may also be poor In conditions of good seeing star twinkling is minimal and images 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 Avoid looking over buildings pavement or any other source of heat as they will cause heat wave disturbances that will distort the image you see through the t
30. letely opaque material 9 Care and Maintenance If you give your telescope reasonable care it will last a life time Store it in a clean dry dust free place safe from rapid changes in temperature and humidity Do not store the tele scope outdoors although storage in a garage or shed is OK Small components like eyepieces and other accessories should be kept in a protective box or storage case Keep the cap on the front of the telescope when it is not in use Your AstroView 120ST telescope requires very little mechani cal maintenance The optical tube is aluminum and has a smooth painted finish that is fairly scratch resistant If a scratch does appear on the tube it will not harm the tele scope If you wish you may apply some auto touch up paint to the scratch Smudges on the tube can be wiped off with a soft cloth and a household cleaner such as Windex or Formula 409 Cleaning the Optics A small amount of dust or a few specks on the glass objective main lens will not affect the performance of the telescope If dust builds up however simply blow it off with a blower bulb or lightly brush it off with a soft camel hair brush Avoid touching optical surfaces with your fingers as skin oil may etch optical coatings 15 To remove fingerprints or smudges from a lens use photo graphic type lens cleaning fluid and lint free optical lens cleaning tissue Do not use household cleaners or eyeglass type cleaning cloth or wipe
31. mateur astronomy Take some time to familiarize yourself with the night sky Learn to recognize the patterns of stars in the major con stellations a star wheel or planisphere available from Orion or from your local telescope shop will greatly help With a little practice a little patience and a reasonably dark sky away from city lights you ll find your telescope to be a never ending source of wonder exploration and relaxation These instructions will help you set up properly use and care for your telescope Please read them over thoroughly before getting started Table of Contents ik Parsist a a es eee ee ee 3 2 PSSOMDLY sacaccscatensetgniuceacesabnwceseecasbounendeis aac eeaunsneseemeemeanecewceereradienccd E OEE E a EE 4 3 Balancing the TSS SCO Case sid ed cee a Ea ae EE E EEEE 6 4 Aligning the Finder Scope sccscaceaj Sectnacscoemeinaaseiantiea nycctbecestaneateacencipestae Ceeseualcancenunaceuedeuteeenaues 7 5 Setting Up and Using the Equatorial MOUnNt pcgesisvvecesect cocssieurescensdnweakeeudstncetsteumencenebeceieuanes 7 6 Using Your Telescope Astronomical Observing sssssssessssrrrsserrrrerrnresrtrrsserrrnrerrnnnrrtene 11 7 Astrophotography seessseseerrrsseeeeirirtttsssstttit tuunata ttrt A AAAA eeee e 14 8 Termrestial VIOWNO eee ere Ta ere eee ee a eee N 15 9 Care and Maintenance nrnna EE E E EEEE 15 gies 6 111 ore L g osm ene Re e ere ee E E E E emeee reer ree 16 Mirror star diagonal 1 25 1 P
32. n the drawtube 15 Then insert an eyepiece into the star diagonal and secure it in place with the thumbscrews on the diagonal Always loosen the thumbscrews before rotating or removing the diagonal or an eyepiece 16 Install the polar axis finder scope into its housing inside the R A axis of the equatorial mount Figure 4 First loosen the three thumbscrews on the housing which is located at the rear of the R A axis Insert the front end of the polar finder the end without the eyeguard into the housing so only about 1 of the polar finder extends from the back of the housing Do this slowly and with a twisting motion to prevent the internal O ring from becoming unseated If it does become unseated you can remove the entire housing from the mount to locate the O ring and reseat it This is done by rotating the entire housing coun terclockwise Once the polar axis finder scope is in the housing tighten the three thumbscrews These thumb screws will be used later to align the finder with the mount s R A axis 17 Remove the objective lens dust cover The AstroView 120ST is now assembled and should appear as pictured in Figure 1 Objective Black nylon lens cell gt alignment Lock ring thumbscrews S Eyepiece Spring loaded tensioner __ Dovetail base La nn Figure 3 The 6x30 finder scope and bracket Pointer Date circle R A setting circle w N Meridian Ring with lt E ___ offsetscale time meridian indi
33. nation the negative sign denotes south of the celestial equator There are 60 minutes in 1 hour of R A and there are 60 arc minutes in 1 degree of declination The telescope s R A setting circle is scaled in hours from 1 through 24 with small lines in between representing 10 min ute increments The upper set of numbers apply to viewing in the Northern Hemisphere while the numbers below them apply to viewing in the Southern Hemisphere The Dec set ting circle is scaled in degrees 10 Before you can use the setting circles to locate objects the mount must be accurately polar aligned and the setting cir cles must be calibrated The declination setting circle was calibrated at the factory and should read 90 when the tele scope optical tube is pointing exactly along the R A axis Calibrating the Right Ascension Setting Circle 1 Identify a bright star near the celestial equator and look up its coordinates in a star atlas 2 Loosen the R A and Dec lock levers on the equatorial mount so the telescope optical tube can move freely 3 Point the telescope at the bright star whose coordinates you know Center the star in the telescope s eyepiece Lock the R A and Dec lock levers 4 Loosen the large thumbscrew just above the R A setting circle and rotate the R A setting circle so the pointer indi cates the R A coordinate listed for the bright star in the star atlas Do not retighten the thumbscrew when using the R
34. ography can be success fully attempted with the AstroView 120ST Moon Photography This is perhaps the simplest form of astrophotography as no motor drive is required All that is needed is a T ring for your specific camera model Connect the T ring to your camera body and then thread the T ring onto the rear of the focuser drawtube remove the star diagonal first Now you re ready to shoot Point the telescope toward the Moon and center it within the camera s viewfinder Focus the image with the telescope s focuser Try several exposure times all less than 1 second depending on the phase of the moon and the ISO film speed of the film being used A remote shutter release is recommended as touching the camera s shutter release can vibrate the camera enough to ruin the exposure This method of taking pictures is the same method with which a daytime terrestrial photograph could be taken through the AstroView 120ST Planetary Photography Once basic Moon photography has been mastered it s time to get images of the planets This type of astrophotography also works to get highly magnified shots of the Moon In addition to the T ring you will need a Universal 1 25 Camera Adapter The EQ 3 Motor Drive System single or dual axis is also required This is because a longer exposure is necessary which would cause the image to blur if no motor drive was used for tracking The equatorial mount must be accurately polar aligned too
35. or power of a telescope simply divide the focal length of the telescope by the focal length of the eyepiece the number printed on the eyepiece Telescope Focal Length mm Eyepiece Focal Length mm Magnification For example the AstroView 120ST which has a focal length of 600mm used in combination with a 25mm eyepiece yields a power of 600 25 24x Every telescope has a useful limit of power of about 45x 60x per inch of aperture Claims of higher power by some tele scope 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 fun damental law of optics The steadiness of the air the seeing will limit how much magnification an image can tolerate Always start viewing with your lowest power longest focal length eyepiece in the telescope After you have located and looked at the object with it 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 Use of 2 Eyepieces Another nice feature of the AstroView 120ST is its ability to use either 1 25 or 2 barrel diameter eyepieces
36. place 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 you specific legal rights and you may also have other rights which vary from state to state For further warranty service information con tact Customer Service Department Orion Telescopes amp Binoculars 89 Hangar Way Watsonville CA 95076 800 676 1343 Orion Telescopes amp Binoculars 89 Hangar Way Watsonville CA 95076 Customer Support Help Line 800 676 1343 Day or Evening
37. re position the object within the field of view of the main telescope s eyepiece Focusing the Telescope Practice focusing the telescope in the daytime before using it for the first time at night Start by turning the focus knob until the focuser drawtube is near the center of its adjustment range Insert the star diagonal into the drawtube and an eyepiece into the star diagonal secure with the thumbscrews Point the telescope at a distant subject and center it in the field of view Now slowly rotate the focus knob until the object comes into sharp focus Go a little bit beyond sharp focus until the image just starts to blur again then reverse the rotation of the knob just to make sure you hit the exact focus point The telescope can only focus on objects at least 50 to 100 feet away Do You Wear Eyeglasses If you wear eyeglasses you may be able to keep them on while you observe if your eyepieces have enough eye relief to allow you to see the whole field of view You can try this 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 Calculating the Magnification It is desirable to have a range of eyepieces of different focal lengths to allow viewing over a range of magnifications To calculate the magnification
38. s as they often contain undesirable additives like silicone which don t work well on precision optics Place a few drops of fluid on the tissue not directly on the lens wipe gently then remove the fluid with a dry tissue or two Do not polish or rub hard when cleaning the lens as this will scratch it The tissue may leave fibers on the lens but this is not a problem they can be blown off with a blower 10 Specifications Optical tube Seamless aluminum Objective lens diameter 120mm 4 7 Objective lens crown and flint achromatic air spaced diffraction limited Objective lens coating fully coated with multi coatings Focal length 00mm Focal ratio f 5 bulb Never disassemble the telescope or eyepieces to clean opti cal surfaces Eyepieces 25mm and 10mm Pl ssls fully coated 1 25 Magnification 24x with 25mm 60x with 10mm Focuser Rack and pinion accepts 1 25 or 2 accessories Diagonal 90 star diagonal mirror type 1 25 Finder scope 6x magnification 30mm aperture achromatic crosshairs Mount German type equatorial Tripod Aluminum Motor drives Optional One Year Limited Warranty This Orion AstroView 120ST Equatorial refractor is warranted against defects in materials or workman ship for a period of one year from the date of purchase This warranty is for the benefit of the original retail purchaser only During this warranty period Orion Telescopes amp Binoculars will repair or re
39. the knurled ring clamps finger tight to secure the telescope in position 11 Now attach the two slow motion cables to the R A and Dec worm gear shafts of the equatorial mount by positioning the small screw on the end of the cable over the indented slot on the worm gear shaft Then tighten the screw 12 To place the finder scope in the finder scope bracket Figure 3 first unthread the two black nylon thumbscrews until the screw ends are flush with the inside diameter of the bracket Place the O ring that comes on the base of the bracket over the body of the finder scope until it seats into the groove on the middle of the finder scope Slide the eyepiece end narrow end of the finder scope into the end of the bracket s cylinder that does not have the alignment thumbscrews while pulling the chrome spring loaded ten sioner on the bracket with your fingers Push the finder scope through the bracket until the O ring seats just inside the front opening of the bracket cylinder Now release the tensioner and tighten the two black nylon thumbscrews a couple of turns each to secure the finder scope in place 13 Insert the base of the finder scope bracket into the dove tail slot on the top of the focuser Lock the bracket into position by tightening the knurled thumbscrew on the dovetail slot 14 Remove the cover cap on the end of the focuser Insert the chrome barrel of the star diagonal into the focuser and secure with the thumbscrew o
40. through the polar finder at a distant object during the day Focus the polar finder so that the images and reticle are sharp by rotating the eyepiece end of the finder Notice that the reticle pattern consists of a crosshair with a circle around the middle On the circumference of this circle is a tiny circle this is where Polaris will be placed for accurate polar alignment once the finder is properly aligned Alignment of the polar finder is best done during the day before going out into the field at night Aligning the Polar Axis Finder Scope Aligning the polar axis finder scope so that it will accurately point at the true north pole is a two step procedure First the polar finder must be rotated in its housing so that the small circle in which Polaris will be placed in is in the proper initial position Next the polar axis finder must be adjusted so that it points directly along the mount s R A axis We will start by aligning the polar finder rotationally Refer to Figure 4 1 Loosen the large thumbscrew just above the R A setting circle Rotate the R A setting circle until the line above the 0 on the setting circle lines up with the pointed indicator Azimuth fine adjustment knobs Tripod attachment knob Figure 8 For polar alignment position the tripod so that the N label at the base of the mount faces north The two azimuth fine adjustment knobs above it are used to make small adjustments to the mount s azimut
41. through the telescope you ll see it drift slowly across the field of view To keep it in the field if your equatorial mount is polar aligned just turn the R A slow motion control The Dec slow motion control is not needed for tracking Objects will appear to move faster at higher magnifications because the field of view is narrower Optional Motor Drive An optional DC motor drive system can be mounted on the AstroView s equatorial mount to provide hands free tracking Objects will then remain stationary in the field of view without any manual adjustment of the R A slow motion control The motor drive system is necessary for astrophotography Understanding the Setting Circles The setting circles on an equatorial mount enable you to locate celestial objects by their celestial coordinates Every astronomi cal object resides in a specific location on the celestial sphere That location is denoted by two numbers its right ascension R A and declination Dec In the same way every location on Earth can be described by its longitude and latitude R A is similar to longitude on Earth and Dec is similar to latitude The R A and Dec values for celestial objects can be found in any star atlas or star catalog So the coordinates for the Orion Nebula listed in a star atlas will look like this R A 5h 35 4m Dec 5 27 That s 5 hours and 35 4 minutes in right ascension and 5 degrees and 27 arc minutes in decli
42. tor A full Moon is too bright and devoid of surface shadows to yield a pleasing view Try using a Moon Filter to dim the Moon when it is very bright It simply threads onto the bottom of the eyepieces you must first remove the eyepiece from the star diagonal to attach the Moon filter B The Sun You can change your nighttime telescope into a daytime Sun viewer by installing an optional full aperture solar filter over the front opening of the AstroView 120ST EQ The primary attraction is sunspots which change shape appearance and location daily Sunspots are directly related to magnetic activ ity in the Sun Many observers like to make drawings of sunspots to monitor how the Sun is changing from day to day Important Note Do not look at the Sun with any optical instrument without a professionally made solar filter or permanent eye damage could result 13 C The Planets The planets don t stay put like the stars they don t have fixed R A and Dec coordinates so you ll have to refer to charts published monthly at our website www telescope com or in monthly magazines like Astronomy Sky amp Telescope to locate them Venus Mars Jupiter and Saturn are the bright est objects in the sky after the Sun and the Moon Not all four of these planets are normally visible at any one time JUPITER The largest planet Jupiter is a great subject to observe You can see the disk of the giant planet and watch the ever changin
43. uatorial mount is properly oriented 7 Thread the counterweight shaft into the equatorial mount at the base of the declination axis until tight Make sure the casting at the top of the bar is threaded clockwise as far as it will go before attaching the shaft 8 Remove the knurled toe saver retaining screw on the bottom of the counterweight shaft and slide both counter weights onto the shaft Make sure the counterweight lock knobs are adequately loosened so the metal pin inside the counterweight is recessed enough to allow the counter weight shaft to pass through the hole Position the counterweights about halfway up the shaft and tighten the lock knobs Replace the toe saver on the end of the bar It prevents the counterweights from falling on your foot if the lock knobs happen to come loose 9 Attach the two tube rings to the equatorial head using the bolts that come installed in the rings Remove the bolts then push them with the washers still attached up through the holes in the tube ring mounting plate on the top of the equa torial mount and rethread them into the bottom of the tube rings Tighten the bolts securely with the smaller wrench Open the tube rings by loosening the knurled ring clamps 10 Lay the telescope optical tube in the tube rings at about the midpoint of the tube s length Rotate the tube in the rings so the focus knobs are on the underside of the telescope Close the rings over the tube and tighten
44. ver tighten or the threads may strip Refer to Figure 1 during the assembly pro cess During assembly and anytime for that matter DO NOT touch the surfaces of the telescope objective lens or the lenses of the finder scope or eyepieces with your fingers The optical surfaces have delicate coatings on them that can eas ily be damaged if touched inappropriately NEVER remove any lens assembly from its housing for any reason or the product warranty and return policy will be voided 1 Lay the equatorial mount on its side Attach the tripod legs one at a time to the mount using the bolts installed in the tops of the tripod legs Remove the bolt from the leg line up the holes in the top of the leg with the holes in the base of the mount and reinstall the bolt so it passes through the leg and the mount Tighten the wingnuts only finger tight for now Note that the accessory tray bracket attachment point on each leg should face inward 2 Tighten the leg lock knobs at the base of the tripod legs For now keep the legs at their shortest fully retracted length you can extend them to a more desirable length later after the scope is completely assembled 3 With the tripod legs now attached to the equatorial mount stand the tripod upright be careful and spread the legs apart enough to connect each end of the accessory tray bracket to the attachment point on each leg Use the screw that comes installed in each attachment point to do t
45. xis Finder When using the polar finder in the field at night you will need a red flashlight to illuminate the finder s reticle Shine the flashlight at an angle into the front opening in the R A axis Do not shine it directly into the opening or the light will be too bright and you will also obstruct the view of the polar finder It may be helpful to have a friend hold the flashlight while you look through the polar finder For most accurate polar alignment you will need to know the approximate longitude of your observing site This information can be obtained by looking at a local map Now you must figure the difference between the longitude of your observing site and the closest standard time meridian The standard time meridians are 75 90 105 and 120 for the 48 continental states 150 and 165 for Hawaii and Alaska Choose the standard time meridian that is closest in value to your local longitude and then calculate the difference If your local longitude has a value less than the closest standard time meridian then you are east of the standard time meridian by the calculated amount If your local longitude has a value greater than the closest standard time meridian then you are west of the standard time meridian by the calculated amount For example if you are in Las Vegas which has a longitude of 115 then the closest standard time meridian is 120 The difference between these two numbers is 5 Since Las Vegas
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