Orion XT4.5 User's Manual
Contents
1. Altitude and Azimuth The Dobsonian base of the SkyQuest XT4 5 permits motion of the telescope along two axes altitude up down and azimuth left right see Figure 10 This is very convenient since up down and left right are the most natural ways that people aim As a result pointing the telescope is exceptionally easy Simply take hold of the telescope Figure 11 and move it left Altitude Azimuth Figure 10 The SkyQuest has two axes of motion altitude up down and azimuth left right or right so the base rotates about its central azimuth bolt and move it up or down so the altitude side bearings rotate in the base s cradle Both motions can be made simultaneously and in a continuous manner for easy aiming Move the telescope gently let it glide In this way you can point the telescope to any position in the night sky from horizon to horizon One of the unique features of the SkyQuest XT is the Navigation Knob located underneath the telescope tube near the open end This knob makes for easy smooth movement of the telescope You can use it to move the telescope in both the azimuth and altitude directions You may find it convenient to hold your other hand near the Figure 11 Try grasping the telescope as shown for easiest pointing The left hand uses the Navigation Knob as a handle while the right hand is on the rear of the tube rear of the telescope tube to steady it while moving and a2. Mee PEETI i i i is a Sean ie a period of one year from the date of purchase This warranty is for the benefit of the original retail purchaser only During E R fee this warranty period Orion Telescopes amp Binoculars will repair or replace at Orion s option any warranted instrument Sh fi M RISK Wiel i e i Ee ae Ta that proves to be defective provided it is returned postage paid to Orion Warranty Repair 89 Hangar Way Watsonville SY Se CA 95076 If the product is not registered proof of purchase such as a copy of the original invoice is required ail See This warranty does not apply if in Orion s judgment the instrument has been abused mishandled or modified nor Set Lis Magee SSN X lt a does it apply to normal wear and tear This warranty gives you specific legal rights and you may also have other rights Le a sr pa EE i P i i ERSE jee which vary from state to state For further warranty service information contact Customer Service Department Orion e Soe Wiser he eh tee Telescopes amp Binoculars P O Box 1815 Santa Cruz CA 95061 800 676 1343 e eer EE TE E EE ESE E a a a E s A T A A MAYAN E T A A AU Aa E NAVAN E AVA EA AYN YVAN TAR ANA AU A N N T S RRA LARA KAAN kiki ttbi kiki ttbi kiki tee ttbi LARA RAA LARA KAAN LRA ktkt LERA ttbi kiki ih t h t H t DO ieena ANS ATO S AAAS E S TOS AAAS ANAS AVG NE AAAS MAS AAAS AAR S AAS A o AAAS TS AANA AO AS ANAS AAAS AMX AO ANN Bony Mi EASA ME
3. field of view This is easy to do with the SkyQuest XT4 5 because of its smooth motions on both axes As the object moves off toward the edge of the field of view you just light ly 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 inher ent 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 10 Remember that objects appear to move across the field of view faster at higher magnifications This is because the field of view becomes narrower Eyepiece Selection By using eyepieces of varying focal lengths it is possible to attain many magnifications with the SkyQuest XT4 5 The telescope comes with two high quality Sirius Plossl eye pieces a 25mm which gives a magnification of 36x and a 10mm which gives a magnification of 91x Other eyepieces can be used to achieve higher or lower powers It is quite common for an observer to own five or more eyepieces to access a wide range of magnifications This allows the observer to choose the best eyepiece to use depending on the object being viewed At least to begin with the two sup plied eyepieces will suffice nicely Whatever you choose to view a
4. ments can be made to the primary mirror To start turn the thin thumbscrews that lock the primary mirror in place a few turns each Figure 19 Now try tightening or loosening one of the wide collimation thumb screws with your fingers Figure 20 Look into the focuser and see if the secondary mirror reflection has moved closer to the center of the Figure 19 The three thin thumbscrews that lock the primary mirror in place must first be loosened before any adjustments can be made primary You can tell this easily with the collimation cap and mirror center mark by simply watching to see if the dot of the collimation cap is moving closer or further away from being centered in the ring of the primary mirror mark When you have that dot centered as much as is possible in the ring your primary mirror is collimated The view through the collimation cap should resemble Figure 16e Re tighten the locking thumbscrews A simple star test will tell you whether the optics are accurately collimated Figure 20 The tilt of the primary mirror is adjusted by turning one or more of the three wide collimation thumbscrews Star Testing the Telescope When it is dark point the telescope at a bright star and accurately center it in the eyepiece s field of view Slowly de focus the image with the focusing knob If the telescope is correctly collimated the expanding disk should be a perfect circle Figure 21 If the
5. Orient the spacer so the narrow end is closest to the knob Thread the entire assembly into the hole with the brass insert in the tele scope s altitude side bearing until tight The end ring of the spring should seat onto the narrow end of the spacer Repeat this procedure for the other altitude side bearing 3 Attach a pull loop to the free end of each spring Slide the loop through the opening in the ring on the end of the spring 4 Now pull each spring down using the pull loop and posi tion the spring s end ring over the head of the black Phillips screw installed in step 1 and onto the narrow part of the nylon spacer as shown in Figure 7 You needn t attach both springs simultaneously one at a time is fine The CorrecTension system is now installed and engaged If you wish to remove the telescope tube from the base you will first need to disconnect the springs from the posts on the Dobsonian base Remember to position the tube upright before doing this or the tube will fall over The springs will remain captive on the altitude side bearings so they will not get lost Installing the Finder Scope The SkyQuest XT4 5 comes with a high quality 6x26 correct image achromatic finder scope Figure 8a The 6 means it magnifies 6 times the 26 means it has a 26mm effective diameter lens and the correct image means the image in the finder scope will appear right side up just like the view through your naked ey
6. Sete MD Poo KAN SANY rela tes POO KANI EA KAN RIENNON IOIEN OS ANOSSA MD Poe KAn POO iat Rete POO KANI EA KAN SACOS KAN PORE MPO ISN KANI RISAIN fete bits eats LAS ah SKY eee ee SS Se e SS Se SS Se SE ee Se SS DED SS Se Ss SS a eee See See Se Orion Telescopes amp Binoculars Post Office Box 1815 Santa Cruz CA 95061 Customer Support Help Line 800 676 1343 Day or Evening 16
7. a blower bulb or compressed air Then apply some clean remove the secondary mirror from its holder for cleaning To clean ing fluid to a tissue never directly on the optics Wipe the lens gently the secondary mirror follow the procedure described below for in a circular motion then remove any excess fuild with a fresh lens cleaning the primary mirror tissue Oily finerprints 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 tis sue on each area Never reuse tissues To clean the primary mirror carefully remove the mirror cell from the telescope To do this you must remove the three screws that connect the entire mirror cell to the steel tube These screws are located on the outer edge of the mirror cell casing Now remove the mirror from the mirror cell by removing the three mirror clips that secure the mirror in its cell Use a Phillips head screwdriver to unthread the mirror clip anchor screws Next hold the mirror by its edge and remove it from the mirror cell Be care ful not to touch the aluminized surface of the mirror with your fingers Set the mirror on a clean soft towel Fill a clean sink free of abrasive cleanser with room temperature water a few drops of liquid dishwashing detergent and if possible a cap full of rubbing alcohol Submerge the mirror aluminized face up in the water and Cleaning Mirr
8. changing phases you ll get a new view of the Moon every night The best time to observe our one and only natural satellite is during a partial phase that is when the Moon is NOT full During partial phases shadows are cast on the sur face which reveal more detail especially right along the border between the dark and light portions of the disk called the terminator A full Moon is too bright and devoid of sur face shadows to yield a pleasing view Use an optional 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 focuser to attach a filter You ll find that a Moon filter improves viewing comfort and also helps to bring out subtle features on the lunar surface 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 a SkyQuest XT4 5 The primary attraction is sunspots which change shape appearance and location daily Sunspots are directly related to magnetic activity 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 C The Bright Planets The planets don t stay put like the stars so to find them you should refer t
9. deci sion must be made what to look at What to Expect So what will you see with your telescope You should be able to see bands on Jupiter the rings of Saturn craters on the moon the waxing and waning of Venus and possibly hun dreds of deep sky objects Do not expect to see any color as you do in NASA photos since those are taken with long exposure cameras and have false color added Our eyes are not sensitive enough to see color in deep sky objects except in a few of the brightest ones Remember that you are seeing these objects using your own telescope with your own eyes The object you see in your eyepiece is in real time and not some conveniently provided image from an expensive space probe Each session with your telescope will be a learning experience Each time you work with your telescope it will get easier to use and stellar objects will become easier to find Take it from us there is big difference between looking at a well made full color NASA image of a deep sky object in a lit room during the daytime and seeing that same object in your telescope at night One can merely be a pretty image someone gave to you The other is an experience you will never forget A The Moon With its rocky surface the Moon is one of the easiest and most interesting targets to view with your telescope Lunar craters marias and even mountain ranges can all be clearly seen from a distance of 238 000 miles away With its ever
10. 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 mag nitude 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 visu al magnitude of 9 or lower Many beginners start with the Messier objects which represent some of the best and bright est 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 constella tion 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 cen ter it on the crosshairs Next look again at the star chart and find another suitably bright star near the bright star currently cente
11. flush with the top surface of the top baseplate 6 Insert the T nut K into the center hole of the ground base plate A so the nut s flanged top is on the same side of the baseplate as the Teflon pads Thread the large hex head bolt G with a 3 8 washer F attached up through the ground baseplate and through the T nut until it is tight 7 Now position the top baseplate D with side panels attached over the ground baseplate and lower it so the bolt goes through the nylon spacer in the center hole of the top baseplate Now thread the remaining 3 8 washer H and lock nut I onto the bolts shaft You might need to hold the bolt s head in place with another crescent wrench or pliers Tighten the lock nut with the wrench just enough to allow a slight separation of the top and bottom baseplates when the mount is lifted The purpose of the lock nut is merely to keep the two baseplates from coming apart when moving the tel escope Over tightening the lock nut I will make the mount difficult to rotate in the azimuthal horizontal direction 8 The rubber bumper L provides a convenient stop for the telescope s altitude motion it prevents the telescope mirror cell from being knocked against the hard surface of the base s front brace At the bottom of the interior surface of the front brace you will notice a small index mark engraved Remove the backing from the rubber bumper and position the bumper over the index mark as sh
12. in a case to prevent any dust and moisture from accumulating on exposed surfaces The telescope requires very little mechanical maintenance The optical tube is made of steel and has a smooth painted finish that is fairly scratch resistant If a scratch does appear on the tube it will not harm the telescope 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 Refer to Appendix B for detailed instructions on how to clean the optics of the SkyQuest XT4 5 7 Specifications Focal Length 900mm Aperture 114mm 4 5 Focal Ratio f 7 9 Mirror Coatings aluminum with SiO overcoat 89 reflective Minor Axis of secondary mirror 28mm Weight 17 6 lbs tube and base Tube Length 35 Tube Outer Diameter 5 5 13 Appendix A Collimation Aligning the Mirrors Collimation is the process of adjust ing the mirrors so they are perfectly aligned with one another Your tele scope s optics were aligned at the factory and should not need much adjustment unless the telescope is handled roughly Accurate mirror alignment is important to ensure the peak performance of your telescope so it should be checked regularly Collimation is relatively easy to do and can be done in daylight To check collimation remove the eye piece and look down the focuser drawtube You should see the sec ondary mirror
13. one of the three alignment set screws while tightening the other two as depicted in Figure 18 The goal is to center the primary mirror reflection in the secondary mirror as in Figure 16d Don t worry that the reflection of Figure 17 Jo center the secondary mirror under the focuser hold the secondary mirror holder in place with your fingers while adjusting the center screw with the Phillips head screwdriver Do not touch the mirror s surface Figure 18 Adjust the tilt of the secondary mirror by loosening or tightening the three alignment set screws with a 2mm Allen wrench the secondary mirror the smallest circle with the collimation cap dot in the center is off center You will fix that in the next step Adjusting the Primary Mirror The final adjustment is made to the primary mirror It will need adjustment if as in Figure 16d the secondary mirror is centered under the focuser and the reflection of the primary mirror is centered in the secondary mirror but the small reflection of the secondary mir ror with the dot of the collimation cap is off center The tilt of the primary mirror is adjusted with three spring loaded col limation thumbscrews on the back end of the optical tube bottom of the primary mirror cell these are the wide thumbscrews The other three thin thumbscrews lock the mirrors position in place these thin thumbscrews must be loosened before any collimation adjust
14. pointed towards a bright surface such as white paper or wall Placing a piece of white paper in the telescope tube opposite the focuser in other words on the other side of the secondary mirror will also be helpful in collimating the secondary mirror Using a 2mm Allen wrench loosen the three small alignment set screws in the center hub of the 4 vaned spider several turns Now hold the secondary mirror holder stationary be careful not to touch the mirror s surface while turning the center screw with a Phillips head screwdriver See Figure 17 Turning the screw clockwise will move the secondary mirror toward the front Opening of the optical tube while turning the screw counter clockwise will move the secondary mirror toward the primary mirror When making these adjustments be care ful not to stress the spider vanes or they may bend When the secondary mirror is cen tered in the focuser drawtube rotate the secondary mirror holder until the reflection of the primary mirror is as centered in the secondary mirror as possible It may not be perfectly cen tered but that is OK Now tighten the three small alignment screws equally to secure the secondary mirror in that position This adjustment will rarely if ever need to be done If the entire primary mirror reflection is not visible in the secondary mirror as in Figure 16c you will need to adjust the tilt of the second ary mirror This is done by alternately loosening
15. INSTRUCTION MANUAL Orion SkyQuest XT4 5 Dobsonian Reflector 9804 _ 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 P O Box 1815 Santa Cruz CA 95061 IN 164 Rev A Secondary mirror holder with 4 vane spider not visible Finder scope Finder scope bracket Focuser Eyepiece Navigation Knob JA Carry handle Altitude Side Bearing CorrecTension system l Primary Eyepiece rack gt gt i yep mirror cell s Plastic foot Figure 1 The SkyQuest XT4 5 parts diagram Welcome to an exciting new world of adventure Your SkyQuest XT4 5 Dobsonian is a high quality opti cal instrument designed to bring you dazzling views of the outer reaches of our universe Easy enough for kids to use and portable enough for anyone to carry the SkyQuest XT4 5 will provide fun and entertain ment for the entire family Whether you are brand new to amateur astronomy or a seasoned stargazer get ready for many evenings of enjoyment and fascination Before venturing into the night with your new tele scope we recommend that you read through this instruction manual Not only does it provide accurate directions for assembly and use but it also serves as a guide for your first explorations in the sky It is not necessary to immediately read the appen
16. al observation of astronomical objects in the night sky Like all Dobsonians it is not well suited for daytime terrestrial usage This is due to the inverted images the Newtonian reflector optics provide and the low eyepiece height when pointed near the horizon We recommend get ting started during the day with the telescope but remember that this is not the intended use If you find that you want to do more daytime viewing of landscapes and vistas you may want to consider purchasing a spotting scope Remember never point the telescope at or near the Sun Figure 9 a use while sitting b You can use the telescope while standing by placing it on a sturdy table c If the table is too tall try something a bit shorter like a milk crate without using a proper solar filter over the front aperture Sit Down or Stand Up One of the great assets of the SkyQuest XT4 5 is its extreme ly portable size Due to its overall short height most adults will find that observing while sitting on a chair or stool is most comfortable If wanting to stand a sturdy table of appropriate height will provide an adequate platform on which to place the telescope Other platforms such as a milk crate can also be employed in order to achieve a range of eyepiece heights Figure 9 Younger children will find that the telescope is a perfect height for them to use while standing this is one of the reasons that it is ideal for budding young astronomers
17. assembly concerns the Dobsonian base Assembly of the Dobsonian base Refer to Figure 2 during base assembly The base need only be assembled once The assembly process takes about 30 minutes and requires a Phillips screwdriver and an adjustable crescent wrench When tightening screws tighten them until firm but be careful not to strip the holes by over tightening Children under the age of 12 should work with an adult Figure 2 Exploded view of the Dobsonian base h Screw the plastic feet into the underside of the ground baseplate A using the self tapping wood screws provided with a Phillips screwdriver Insert the screws through the feet and thread them into the predrilled starter holes 2 Loosely attach the front brace B to the two side panels C with four of the base assembly screws in the predrilled holes The side panels should be oriented so the SkyQuest labels are facing outward Do not completely tighten the screws yet 3 Attach the two sides C with the front brace attached to the top baseplate D with the remaining six base assembly screws in the predrilled holes Tighten all six screws 4 Tighten the four side screws installed earlier Press a trim cap onto the heads of each of these screws 5 Insert the white nylon bushing E into the hole in the cen ter of the top baseplate D Tap the nylon bushing in so it goes all the way into the top baseplate The nylon bushing should be
18. be adjusted again Aiming Pointing the Telescope Now that the finder scope is aligned the telescope can be quickly and accurately pointed at anything you wish to observe The finder scope has a much wider field of view than the telescope s eyepiece and therefore it is much easier to first center an object in the finder scope Then if the finder scope is accurately aligned the object will also be centered in the telescope s field of view Start by once again moving the telescope until it is pointed in the general direction of the object you want to see Some observers find it convenient to sight along the tube to do this Now look in the finder scope If your general aim is accurate the object should appear somewhere in the finder scope Make small adjustments to the telescope s position until the object is centered on the finder s crosshairs Now look in the telescope s eyepiece and enjoy the view Magnification Now that the object you want to view is well centered in the 25mm eyepiece you may want to increase the magnification to get a closer view Loosen the thumbscrew on the focuser drawtube and remove the eyepiece Insert the 10mm eye piece in the focuser then tighten the thumbscrew If you were careful not to bump the telescope the object should still be centered within the field of view Notice that the object being viewed is now larger but somewhat dimmer The SkyQuest XT4 5 is designed to accept any eyepiec
19. centered in the drawtube as well as the reflection of the primary mirror centered in the secondary mirror and the reflection of the secondary mirror and your eye centered in the reflection of the pri mary mirror as in Figure 16a If anything is off center as in Figure 16b proceed with the following colli mation procedure The Collimation Cap and Mirror Center Mark Your SkyQuest XT4 5 comes with a collimation cap This is a simple cap that fits on the focuser drawtube like a dust cap but has a hole in the center and a silver bottom This helps center your eye so that colli mation is easy to perform Figures 16b e assume you have the collima tion cap in place In addition to providing the collimation cap you ll notice a tiny ring sticker in the exact center of the primary mirror This center mark allows you to achieve a very precise collimation of the primary mirror you don t have to guess where the center of the mirror is You simply adjust the mirror posi tion described below until the reflection of the hole in the collimation cap is centered inside the ring This center mark is also required for best results with other collimating devices such as Orion s LaserMate Laser Collimator obviating the need to remove the pri mary mirror and mark it yourself NOTE The center ring sticker need not ever be removed from the primary mirror Because it lies directly in the shadow of the secondary mirror its p
20. cope side bearings Now the base and tube are disengaged and can be transported separately When putting the SkyQuest into a vehicle common sense prevails It is especially important that the optical tube does not Knock around this can cause the optics to become mis aligned and could dent the tube We recommend transporting the telescope in a carry case for proper protec tion 4 Observing Tips For many users the SkyQuest XT4 5 telescope will be a major leap into the world of amateur astronomy This section is intended to get you ready for your first voyage through the night sky Site Selection Pick a location away from streetlights and bright yard lighting Avoid viewing over rooftops and chimneys as they often have warm air currents rising from them which distort the image seen in the eyepiece Similarly you should not observe through an open window from indoors Better yet choose a site out of town away from any light pollution You ll be stunned at how many more stars you ll see Most importantly make sure that any chosen site has a clear view of a large portion of the sky Cooling the Telescope All optical instruments need time to reach thermal equilibri um to achieve maximum stability of the lenses and mirrors which is essential for peak performance When moved from a warm indoor location outside to cooler air or vice versa a telescope needs time to cool or warm to the outdoor tem perature The b
21. dix sections at the end of the manual they contain detailed infor mation regarding aligning and cleaning the telescope s optics which should not be needed initially 2 Table of Contents Tle NO CIN leeccrevstinaeuec antennae E E E sar 3 2 PS SOMO siesta esate asahauan e E E E E 4 3 USING NOUF NClOSCODG sssrini EA SEENE TENE aE 6 A OPSEIN TIDS ee E E ee eee 9 SAONO BASO oae E E E E EAE R ERER 10 6 Care and Maintenance ccccccseeccceeeeeeeeeeeeeceeeeeseeeecaeeeeeseaeeeeseaeeeesaueesseeeeeseeeesageseesaeees 13 Te P CECOT O e a E tee eeieiecoeeeenesentseaaseaeseeeda 13 Appendix A Collimation Aligning the Mirrors cccccccccsececesceceeeeeseeceseeeeeseseeseeeeeaeeeesauess 14 Appendix B Cleaning the Optics cccccccsecccssececeeeeeeeeeeseeeeeeueeesaecesseeessaeeseueesseeesaueesseeeesaes 15 1 Unpacking The telescope will arrive in two boxes one containing the optical tube assembly and accessories the other containing the unassembled Dobsonian base Be careful unpacking the boxes We recommend keeping the original shipping con tainers In the event that the telescope needs to be shipped to another location or returned to Orion for warranty repair having the proper shipping containers will help ensure that your telescope will Survive the journey intact Make sure all the parts in the Parts List below are present Be sure to check boxes carefully as some parts are small If any thing appears
22. e Figure 7 a To attach the spring to the base grip the pull loop with your index finger and pull down on the spring b While pulling down slip the end ring of the spring over the screw head and onto the narrow part of the nylon spacer then release the pull loop To place the finder scope in the finder scope bracket first unthread the two black nylon screws 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 find er scope into the end of the bracket s cylinder that does not have the alignment screws while pulling the chrome spring loaded tensioner on the bracket with your fingers See Figure 8b Push the finder scope through the bracket until the O ring seats just inside the front opening of the bracket s cylinder Now release the tensioner and tighten the two black nylon screws a couple of turns each to secure the finder scope in place The tips of the tensioner and nylon screws should seat into the wide groove on the rear of the finder scope s body Slide the base of the finder scope bracket into the dovetail holder on the top of the focuser Lock the bracket into posi tion by tightening the knurled thumbscrew on the dovetail holder Inserting an Eyepiece The final step in the assembly process i
23. e with a barrel diameter of 1 25 Magnification or power is deter mined by the focal length of the telescope and the focal length of the eyepiece Therefore by using eyepieces of dif ferent focal lengths the magnification can be varied Magnification is calculated as follows Telescope Focal Length mm Magnification Eyepiece Focal Length mm The SkyQuest XT4 5 Dobsonian has a focal length of 910mm So the magnification with the supplied 25mm eye piece is 910mm 25mm 36x The magnification provided by the 10mm eyepiece is 910mm 10mm 91x The maximum attainable magnification for a telescope is directly related to how much light its optics can collect A tel escope with more light collecting area or aperture can yield higher magnifications than a smaller aperture telescope The maximum practical magnification for any telescope regard less of optical design is about 50x per inch of aperture This translates to about 225x for the SkyQuest XT4 5 Maximum magnifications are achieved only under the most ideal viewing conditions at the best observing sites Most of the time magnifications are limited to 200x or less regard less of aperture This is because the Earth s atmosphere distorts light as it passes through On nights of good seeing the atmosphere will be still and will yield the least amount of distortion On nights of poor seeing the atmosphere will be turbulent which means different densities o
24. embly in a warm area until it is completely dry before reassembling the telescope To clean the secondary mirror it must be removed from the tele scope Do this by holding the secondary mirror holder stationary with your fingers don t touch the mirror itself while unthreading the Phillips head cap screw in the center hub of the 4 vaned spi der Completely unthread the screw from the holder and the holder will come loose in your fingers Be careful not to lose the spring on the Phillips head cap screw a ere eee ee fo em fem eee faa fF earn 0 a E fT tree JO eer 0 a a 0 a a fears fo roan 0 moar fr fT er fo Emre Stearn fF tere 0 ara fF ious fT iar fF per fi are ff eer AED His Gow Me UL Ns GO NG UN ee i GER Me Ge Ns GER MN GO ls GS Mis Ge Basle GR Nise GEM BNNs Gow Miss GER LNG Gow ANG Gee ANG Gow MING Fee Nt Toe SUNG Fee NG Toe SUNG Toe HUNG DAS ONG Fee MN DANN Hee Bet SRO A NR CTE E Ce NOC I Te NCE ROC ICT Ne ed EA N A NIC NC EN N A SCTE EA AR NO ICT NC et NC eS RC E AR N SIC Te Nd NI esaa ES A A NIT CIID AYE AITO CTD N ANAT IAT ANIA ANT a a ANT AIT AI ANT ATG AO AA AT ANNA ASTD ANG ioe ee ASAE AUT MCSA TIALS ACE ANUS HATTA ATS ATTA AVA HLS AUTRE ATRL TURE UTS ASUS TRUTHS AAMAS AMS Re eS Men m RA Miesai a Ge en One Year Limited Warranty ae FERN Se SIN yae ne TE ANKY rE This Orion SkyQuest XT Dobsonian Reflecting Telescope is warranted against defects in materials or workmanship for ERSA s i
25. f air are rapidly mixing This causes significant distortion of the incoming light which prevents sharp views at high magnifications Keep in mind that as magnification is increased the bright ness of the object being viewed will decrease this is an inherent principle of the physics of optics and cannot be avoided If magnification is doubled an image appears four times dimmer If magnification is tripled image brightness is reduced by a factor of nine Carrying the Telescope Moving the SkyQuest XT4 5 is exceptionally easy to do Because the springs of the CorrecTension system hold the optical tube captive on the base the entire telescope can be carried as one unit Simply grab the entire unit by the handle on the tube see Figure 13 and away you go DO NOT TRY TO CARRY THE TELESCOPE BY THE NAVI GATION KNOB ONLY USE THE CARRYING HANDLE Make sure that the thumbscrews that secure the eyepiece in the focuser are tightened or it may fall out during transport Figure 13 Transporting the SkyQuest XT4 5 is exceptionally easy Just grab the handle and go Better yet remove the eyepiece from the focuser and store it in an appropriate eyepiece accessory case If you wish to carry the optical tube and base separately sim ply disengage the CorrecTension springs by unhooking them from the posts on the base using the pull loops Make sure the tube is positioned upright before doing this The springs remain captive on the teles
26. gnifica tions 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 which tend to scatter light reducing an Big Dipper in Ursa Major MEGREZ 2 4 1 9 2 5 MAGNITUDES Figure 14 Megrez connects the Big Dipper s handle to it s pan It is a good guide to how conditions are If you can not see Megrez a 3 4 mag star then conditions are poor object s brightness One good way to tell if conditions are good is by how many stars you can see with your naked eye lf you cannot see stars of magnitude 3 5 or dimmer then con ditions are poor Magnitude is a measure of a star s brightness 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 or other conditions that are hindering your viewing See Figure 14 Let Your Eyes 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 per haps 80
27. igger the instrument and the larger the temperature change the more time will be needed Allow at least 30 minutes for your SkyQuest XT4 5 to equil ibrate If the scope experiences more than a 40 temperature change allow an hour or more In the winter storing the telescope outdoors in a shed or garage greatly reduces the amount of time needed for the optics to stabi lize It also is a good idea to keep the scope covered until the Sun sets so the tube does not heat greatly above the temperature of the outside air Seeing and Transparency 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 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 ma
28. im ing the telescope Focusing the Telescope Insert the low power 25mm eyepiece into the focuser and secure with the thumbscrew Move the telescope so the front Open end is pointing in the general direction of an object at least 1 4 mile away Now with your fingers slowly rotate one of the focuser knobs 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 ve hit the exact focus point If you have trouble focusing rotate the focuser knob so the drawtube is in as far as it will go Now look through the eye piece while slowly rotating the focuser knob in the opposite direction You should soon see the point at which focus is reached Viewing with Eyeglasses If you wear eyeglasses you may be able to keep them on while you observe if the eyepiece has 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 If you suffer from severe astigmatism how ever you may find images noticeably sharper with your glasses on Aligning the Finder Scope The finder scope must be aligned accurately with the telescope for pro
29. image is unsymmetrical the scope is out of collimation The dark shadow cast by the secondary mirror should appear in the very center of the out of focus circle like the hole in a donut If the hole appears off center the telescope is out of collimation If you try the star test and the bright star you have selected is not accurately centered in the eyepiece the optics will always appear out of collimation even though they may be perfectly aligned It is critical to keep the star centered so over time you will need to make slight corrections to the telescope s position in order to account for the sky s apparent motion Figure 21 A star test will determine if the telescope s optics are properly collimated An unfocused view of a bright star through the eyepiece should appear as illustrated on the right if optics are perfectly collimated If the circle is unsymmetrical as illustrated on the left the scope needs collimation Collimated Out of collimation Appendix B Cleaning the Optics Cleaning 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 finderscope Never use regular glass cleaner or cleaning fluid designed for eyeglasses 15 Before cleaning with fluid and tissue blow any loose particles off the Handle the mirror and its holder carefully You do not need to lens with
30. ing the finder scope s crosshairs on the exact point you want to look at Then look through the telescope s eyepiece to see if that point is centered in the field of view If it is the job is done If not make the necessary adjustments to the finder scope alignment thumbscrews until the two images match up The finder scope alignment needs to 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 alignment thumbscrews until the star or planet is also centered on the finder s crosshairs The finder scope is an invaluable tool for locat ing objects in the night sky its usage for this purpose will be discussed later in detail Focusing the Finder Scope If when looking through the finder scope the images appear somewhat out of focus you will need to refocus the finder scope for your eyes Loosen the lock ring located behind the objective lens cell on the body of the finder scope see Figure 8a 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 on 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 objective lens cell The finder scope s focus should not need to
31. lways start by inserting your lowest power longest focal length eyepiece to locate and center the object Low magnification yields a wide field of view which shows a larger area of sky in the eyepiece This makes acquiring and centering an object much easier If you try to find and center objects with high power narrow field of view it s like trying to find a needle in a haystack Once you ve centered the object in the eyepiece you can switch to higher magnification shorter focal length eyepiece if you wish This is especially recommended for small and bright objects like planets and double stars The Moon also takes higher magnifications well Deep sky objects however typically look better at medium or low magnifications This is because many of them are quite faint yet have some extent apparent width Deep sky objects will often disappear at higher magnifications since greater magnification inherently yields dimmer images This is not the case for all deep sky objects however Many galax ies are quite small yet are somewhat bright so higher power may show more detail The best rule of thumb with eyepiece selection is to start with a low power wide field and then work your way up in magni fication If the object looks better try an even higher magnification If the object looks worse then back off the magnification a little by using a lower power eyepiece Now that you are all set up and ready to go one critical
32. o Sky Calendar at our website www tele scope com or to charts published monthly in Astronomy Sky amp Telescope or other astronomy magazines Venus Mars Jupiter and Saturn are the brightest objects in the sky after the Sun and the Moon Your SkyQuest XT is capable of show ing you these planets in some detail Other planets may be visible but will likely appear starlike Because planets are quite small in apparent size optional higher power eyepieces are recommended and often needed for detailed observa tions Not all the planets are usually visible at any one time JUPITER The largest planet Jupiter is a great subject for observation You can see the disk of the giant planet and watch the ever changing positions of its four largest moons 11 lo Callisto Europa and Ganymede Higher power eyepieces should bring out the 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 peri od 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 will probably see a bright star close by which is 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
33. 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 5 Astronomy Basics Tracking Celestial Objects The Earth is constantly rotating about its polar axis complet ing 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 into a rate of approx imately 25 per minute or 15 arc seconds per second There are 60 arc minutes in 1 and 60 arc seconds in one arc minute This is called the sidereal rate When you observe any astronomical object you are watch ing a moving target This means the telescope s position must be continuously updated over time to keep an object in the
34. ors You should not have to clean the telescope s mirror very often normally once every year or so Covering the telescope with the dust cap when it is not in use will help prevent dust from accumu lating on the mirrors Improper cleaning can scratch mirror coatings so the fewer times you have to clean the mirrors the bet ter 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 let it soak for several minutes or hours if it is a very dirty mirror telescope are front surface aluminized and overcoated with hard Wipe the mirror underwater with clean cotton balls using extreme silicon dioxide which prevents the aluminum from oxidizing These ly light pressure and stroking in straight lines across the surface coatings normally last through many years of use before requiring Use one ball for each wipe across the mirror Then rinse the mirror re coating which is easily done under a stream of lukewarm water Any particles on the surface can be swabbed gently with a series of clean 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 Dry the bottom and the edges not the mirror surface with a towel Cover the mir ror surface with Kleenex and leave the entire ass
35. own in Figure 3 Press firmly so the adhesive holds the bumper securely in place _ _ Figure 3 Position the rubber bumper stop over the index mark on the inside surface of the front brace Installing the Eyepiece Rack The aluminum eyepiece rack holds three 1 25 eyepieces in a convenient place on the base within easy reach while you re observing A 1 25 barlow can also be held in the rack 7 Figure 4 Using the two supplied screws install the aluminum eyepiece rack in the predrilled holes about halfway down the left side panel of the base You can install the rack so that it can be removed or you can install it so it is permanently attached About halfway down the left side panel of the base you will notice two predrilled starter holes about 4 apart Take the black wood screws that come packaged with the rack and thread them into the starter holes about three turns Then you can keyhole the eyepiece rack onto the wood screws and continue tightening the screws If you want to be able to remove the rack do not tighten the screws too tightly Be certain that the screws are loose enough that you can lift the rack and remove it from the screws through the larger part of the hole If you want to have the rack permanently attached attach the screws tightly Figure 4 Figure 5 Set the optical tube on the cradle of the base so that the altitude side bearings on the tube rest on the whi
36. per use To align it first aim the main telescope in the general direction of an object at least 1 4 mile away the top of a tele phone pole a chimney etc Position that object in the center of the telescope s eyepiece Now look in the finder scope Is the object visible Ideally it will be somewhere in the field of view If it is not some coarse adjust ments of the two finder scope alignment thumbscrews will be needed to get the finder scope roughly parallel to the main tube CALIFORNIA A123456 Naked eye view Sve Figure 12 The view through a reflector telescope is upside down This is true for the SkyQuest XT4 5 The view through the correct image finder scope however will be right side up oriented the same as seen with the naked eye Note The image in the main telescope will appear upside down rotated 180 This is normal for reflector telescopes see Figure 12 Your finder scope is a correct image finder so the images will be right side up With the image in the finder scope s field of view you will now use the two alignment thumbscrews to center the object on the intersection of the crosshairs By turning the alignment thumbscrews you change the line of sight of the finder scope Continue making adjustments to the alignment thumbscrews until the images in both the finder scope and the telescope s eyepiece are exactly centered Check the alignment by moving the telescope to another object and fix
37. red in the finder Keep in mind that the field of view of the finder scope is 6 so you should choose a star that is no more than 6 from the first star if possible Move the telescope slight ly 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 Figure 15 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 gives you inverted images but the finder scope does not 6 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 caps on the front of the scope and on the focuser when it is not in use For maximum protection during storage we rec ommend placing the telescope
38. resence in no way adversely affects the 14 Bottom end of focuser Reflection of your eye Mirror center mark not shown for clarity Edge of r secondary mirror O Reflection of Reflection of secondary mirror holder with spider vanes 3 Primary mirror clip Secon mirror primary mirror Figure 16 Collimating the optics a When the mirrors are properly aligned the view down the focuser drawtube should look like this b With the collimation cap in place if the optics are out of alignment the view might look something like this c Here the secondary mirror is centered under the focuser but it needs to be adjusted tilted so that the entire primary mirror is visible d The secondary mirror is correctly aligned but the primary mirror still needs adjustment When the primary mirror is correctly aligned the dot will be centered as in e optical performance of the tele scope or the image quality That might seem counterintuitive but it s true Aligning the Secondary Mirror With the collimation cap in place look through the hole in the cap at the secondary diagonal mirror Ignore the reflections for the time being The secondary mirror itself should be centered in the focuser drawtube in the direction parallel to the length of the telescope If it isn t as in Figure 16b it must be adjusted It helps to adjust the secondary mir ror in a brightly lit room with the telescope
39. s to insert an eye piece into the telescope s focuser Take the cover cap off the end of the focuser drawtube Loosen the thumbscrews on the focuser drawtube and insert one of the eyepieces Secure it in place by re tightening the thumbscrews The assembly of your SkyQuest Dobsonian is now complete It should appear as shown in Figure 1 The dust cap on the front of the telescope tube should always remain in place when the telescope is not in use It is also a good idea to Focus lock ring Alignment thumb screw _ Figure 8a The 6x26 correct image finder scope and bracket Figure 8b Inserting the finder scope into the finder scope bracket store eyepieces in an eyepiece case and to replace the cover caps on the focuser drawtube and on both ends of the finder scope when the telescope is idle 3 Using Your Telescope It is best to get a feel for the basic functions of the SkyQuest XT4 5 during the day before observing astronomical objects at night This way you will not have to fumble around trying to orient yourself in the dark Find a spot outdoors where you have plenty of room to move around the telescope and where you have a clear view of some object or vista that is at least 1 4 mile away It is not critical that the base be exactly level but it should be placed on somewhat flat ground or pavement to ensure smooth movement of the telescope Keep in mind that the SkyQuest XT4 5 was designed specif ically for visu
40. s you see in books and magazines most will look like dim gray smudges Our eyes are not sensitive enough to see color in deep sky objects except in a few of the brightest ones But as you become more experienced and your observing skills get sharper you will be able to ferret out more and more sub tle details and structure How to Find Deep sky Objects Starhopping Starhopping as it is called by astronomers is perhaps the sim plest 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 clos er 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 12 507 ova ANDROMEDA PS Great Andromeda Galaxy M31 M110 40 a po 35 Pinwheel Galaxy M33 T Figure 15 Starhopping is a good way to locate hard to find objects Refer to a star chart to map a route to the object that uses bright stars as guideposts Center the first star you ve chosen in the finder scope and telescope eyepiece 1 Now move the scope carefully in the direction of the next bright star 2 until it is centered Repeat 3 and 4 The last hop 5 should place the desired object in the eyepiece mind as with any new task that starhopping may seem chal lenging at
41. te plastic pads Position the telescope as shown so that it won t fall down before the CorrecTension System is installed and engaged Placing the Optical Tube on the Dobsonian Base Lift the optical tube and set the altitude bearings on either side of the tube in the cradle of the base The tube will not yet be properly balanced since the CorrecTension system has not been installed Keep the tube positioned upright as shown in Figure 5 for now Installing the CorrecTension XT Friction Optimization System To install the CorrecTension assembly follow these steps while referring to Figure 6 1 Put one of the black nylon spacers on a black Phillips head screw The spacer should be oriented so the narrow end seats against the head of the screw Slip one of the Screw w round knob Altitude side bearing Phillips head screw ee SkuQu 1 4 washer black Black nylon spacers Pull loop Figure 6 Close up view of the CorrecTension System black 1 4 washers over the end of the screw Now thread the screw into the hole in the base side panel just below the cradle The screw will thread into the preinstalled insert in the hole Use a Phillips screwdriver to tighten the bolt Repeat this procedure on the opposite side panel 2 Next insert one of the screws with round plastic knob attached through the end ring of one of the springs Slip a black nylon spacer onto the screw
42. to be missing or broken immediately call Orion Customer Support 800 676 1343 for assistance Parts List Box 1 Optical Tube Assembly and Accessories Qty Description WARNING Never look directly at the Sun through your telescope or its finder scope even for an instant without a professionally made solar filter that completely covers the front of the instrument or permanent eye damage could result Young children should use this telescope only with adult supervision Box 2 Dobsonian Base Qty Description 1 Optical tube assembly 1 Left panel 1 Optical tube Dust cover 1 Right panel 1 25mm Sirius Pl ssl eyepiece 1 25 barrel diameter 1 Front brace 1 10mm Sirius Plossl eyepiece 1 25 barrel diameter 1 Top baseplate 1 Eyepiece rack w mounting wood screws 1 Ground baseplate 1 6x26 Correct Image finder scope w O Ring 10 Base assembly screws 1 Finder scope bracket 4 Trim caps black 2 Spring coils 3 Plastic feet 2 Pull loops 3 Feet attachment wood screws length 3 4 1 Collimation cap 1 Self adhesive rubber bumper 4 Nylon spacers black 1 Large hex head bolt length 2 2 1 4 washers black 2 3 8 washers 2 Phillips head screws black length 1 1 2 eee 1 Nylon spacer white 1 T nut 2 Assembly Now that you have unpacked the boxes and familiarized yourself with all the parts in front of you it s time to begin assembly The optics of the telescope are already installed in the tube so most of the required
43. visible to the naked eye during full daylight lronically 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 The Red Planet makes its closest approach to Earth every two years During close approaches you ll see a red disk and may be able to see the polar ice cap To see sur face detail on Mars you will need a high power eyepiece and very steady air D The Stars Stars will appear like twinkling points of light Even powerful telescopes cannot magnify stars to appear as more than a point 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 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 a variety of 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 Do not expect these subjects to appear like the photograph
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