Celestron XLT series manual

O O m m n n i i X X L L T T S S e e r r i i e e s s T T e e l l e e s s c c o o p p e e s s I I N N S S T T R R U U C C T T I I O O N N M M A A N N U U A A L L ● ● O O m m n n i i X X L L T T 1 1 0 0 2 2 ● ● O O m m n n i i X X L L T T 1 1 2 2 0 0 ● ● O O m m n n i i X X L L T T 1 1 5 5 0 0 ● ● O O m m n n i i X X L L T T 1 1 2 2 7 [...]

2 T T a a b b l l e e o o f f C C o o n n t t e e n n t t s s INTRODUCTION .......................................................................................................................................................... 4 Warning ..............................................................................................................[...]

Using the Lens Cap Apertu re Stop with Refractor Tele scopes ................................................................ 32 ASTROPHOTOGRAPHY ............................................................................................................................... ............ 33 Piggyback P hotography .....................................[...]

Congratulations on your purchase of an Om ni XLT Series telescope. The Omni XLT Series of telescopes come in several different models --- 102mm refractor, 120mm refractor, 150mm Newtonian, 127mm Schmidt- Cassegrain. The Omni Series is made of the highest qualit y materials to ensure stability and durabi lity. All this add s up to a telescope th at [...]

Figure 1-1 Omni XLT 102 Refractor 1 2 3 4 5 6 7 8 9 10 11 12 (Omni XLT 120 Refractor similar) 1. Optical Tube 7. 1.75" Steel Tripod 2. Tube Rings 8. Accessory Tray/ Leg Brace 3. Finderscope 9. Counterweights 4. Eyepiece 10. Counterweight Bar 5. Equatorial Mount 11. Dovetail Slide Bar 6. Latitude Adjustment Screw 12. Objective Lens Shade 5[...]

1 2 4 5 6 7 8 9 10 11 12 3 Figure 1-2 Omni XLT 150 Newtoni an 1. Finderscope 7. 1.75" Steel Tripod 2. Finderscope Bracket 8. Accessory Tray/ Leg Brace 3. Focuser 9. Counterweights 4. Eyepiece 10. Counterweight Bar 5. Tube Rings 11. Dovetail Slide Bar 6. Equatorial Mount 12. Optical Tube 6[...]

1 2 3 4 6 7 8 9 10 11 12 5 Figure 1-3 Omni XLT 127 Schmidt-Cassegrain 1. Optical Tube 7. 1.75" Steel Tripod 2. Finderscope 8. Counterweights 3. Finderscope Bracket 9. Counterweight Bar 4. Equatorial Mount 10. Declination Setting Circle 5. Latitude Scale 11. Dovetail Slide Bar 6. Accessory Tray/ Leg Brace 12. Schmidt Corrector Lens 7[...]

This section c overs the assem bly instructio ns for your Cel estron Om ni XLT te lescope. The e quatorial m ount is exactly the same for all the Omni telescope models and th e optical tubes have some differences which will be noted. Your Omni telescope should be set up indoor the first time so that it is easy to identify the various parts and fami[...]

A A t t t t a a c c h h i i n n g g t t h h e e E E q q u u a a t t o o r r i i a a l l M M o o u u n n t t The equatorial m ount allows you to tilt the telescope’s axis of rotation so that you can tr ack the stars as they move across the sky . The Om ni mount is a German e quatorial m ount that attaches to the tripod head. On one side of the tri[...]

A A t t t t a a c c h h i i n n g g t t h h e e C C e e n n t t e e r r L L e e g g B B r r a a c c e e Exhibit 2-6 1. Remove the accessory tray knob an om the centr al rod. sory tray over the centra l rod so that each arm of the tray is pushi ng against the inside of the tripod legs. . Thread the accessory tray knob on to th e central rod and tigh[...]

mount so th at the polar axis is pointing wards north before the tube assembly and co unterw eights are attached. This will make the polar lignment procedure much easier. Since the fully assembled telescope can be quite heavy, po sitio n the to a I I n n s s t t a a l l l l i i n n g g t t h h e e C C o o u u n n t t e e r r w w e e i i g g h h t t[...]

5. The DEC sl ow moti on knob attaches in the sam e manne r as the R.A. knob. The shaft that the DEC slow motion ount, just below the telescope mounting platform. Once again, you have o shafts to choose from. Use the shaft that is poin ti ng toward the ground. This makes it easy to reach wh ile oking through the telescop e, something which is quite[...]

I I n n s s t t a a l l l l i i n n g g t t h h e e F F i i n n d d e e r r s s c c o o p p e e elescope tube (on r efractors and S chmidt-C assegrain) and nt of the telescope tube (Newtonian), there is a sm all bracket with a set screw in it. This is where the erscope: 1. tment scre ws so they don’t protrude into the bracket. Then slide the rubb[...]

I I n n s s t ta l l l l i i n n g g t t h h e e S S t t a a r r D D i i a a g g o o n n a a l l he st fractors and Sc hmidt- asseg n are ph o attach t Schmidt- assegrain: 1. rn t into (i. o 2. Slide t 3. ighten the set screw on t he visual back to hold the star diago nal in you wish to change t he orientati on of the s tar diagonal, loose n the di[...]

The refracting telescopes can use eyepieces and diagonals of a 2” barrel diameter. To us e a 2” ba rrel eyepiece, the 1 ” eyepiece adapter must first be removed. To do this, simply loosen the two chrome thum bscrews located around e focuser barrel (see figure 2-12) a nd remove the 1 ¼” ad apte r. Once removed, a 2” ey epiece or accessory[...]

B B a a l l a a n n c c i i n n g g t t h h e e M M o o u u n n t t i i n n D D E E C C . amp and r otate the tele scope so that it is on one side of the mount (i.e., as described in the . Release the tube — GRADUALLY — to see which way it rotates around the declinatio n axis. DO NOT LET GO 5. 6. .Tighten the tube ring screws firm ly to hold th[...]

A A d d j j u u s s t t i i n n g g t t h h e e M M o o u u n n t t i i n n A A l l t t i i t t u u d d e e • To increase the latitu d e of the polar axis, tighten the rear latitude adjustm ent screw and loos en the front sc rew (if necessary). • To decrease the latitud e of the polar axis, tighten the fr on t (under the counterweight bar) lati[...]

A telescope is an instrum ent that collects and fo cuses light. Th e nature of the optical design determines how the light is fo c used. ome tele opes, known as re telescopes, known as reflecto rs (Newtonians), use mirrors. Then , the chmidt- ssegrai elescop ses. Each optical design is briefly discussed below: evelope in the early 1600s, is the old[...]

19 Figure 3-3 A A c c u u t t a a w w a a y y v v i i e e w w o o f f t t h h e e l l i i g g h h t t p p a a t t h h o o f f t t h h e e S S c c h h m m i i d d t t - - C C a a s s s s e e g g r r a a i i n n o o p p t t i i c c a a l l d d e e s s i i g g n n Figure 3-2 A The Schmidt-Cassegrain optical system (or Schmidt-Cass for short) uses a co[...]

20 I I m m a a g g e e O O r r i i e e n n t t a a t t i i o o n n he image orientation ch anges depending on how the eyepiece is inse rted into th e telescope. When using the star diagonal with fractors and Schmidt-Cassegrains, the image is right-side-up, but reversed from left-t o-right (i.e., mirror image). If inser ting e eyepiece dire ctly int[...]

21 A A l l i i g g n n i i n n g g t t h h e e F F i i n n d d e e r r s s c c o o p p e e ccurate alignment of the finder makes it easy to fi nd objects with the telescope, especially celestial obj ects. To 1 hoose a target that is in excess of one mile away. This elim inates any possible parallax effect between the 2 and DEC clam ps and point the[...]

D D e e t t e e r r m m i i n n i i n n g g F F i i e e l l d d o o f f V V i i e e w w To e = ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ s section, we can determine the field of v iew using the same 25mm eyepiece th at is supplied standard with all Omni XLT nuing tance apparent field of ea ch eyepiece th at Celestron manufactures is found in th e Cel[...]

Up to this point, this manual covered the assembly and ba sic operation of your teles cope . However, to understand your telescope more thoroughl t the night sky. This section deals with observational astronomy t sky and polar alignment. T T h h e e C C y, you need to know a little abou in general and includ es informa tion on the nigh 23 e e l l e[...]

24 aily motion of the Sun across the sk y is familiar to ev en the m st casua l observer. This dail y trek is not the Sun oving as early astronomers thought, but the result of the Earth ' s rotation. The Earth's rotation also causes the stars to o the same, scribing out a large circle as the Earth completes one rotation. The size of the c[...]

25 L L a a t t i i t t u u d d e e S S c c a a l l e e he easiest way to polar align a telescope is with a latitude scale. Unlike other methods th at require you to find the this example, the distance from the northern hor izon to the celestial pole is always equal to your latitude. If you are observing from Los Angeles, which has a latitude of 34?[...]

26 igning, do NOT move the telescop e in R.A. or DEC. You do not want to move the ar axis. The telescope is used s imply to see where the polar axis is poin ting. Remember, while Polar al elescope itself, but the pol t Like the previous method, this gets yo u close to the pole but not directly on it. The following meth ods help improve your accurac[...]

27 D D e e c c l l i i n n a a t t i i o o n n D D r r i i f f t t M M e e t t h h o o d d o o f f P P o o l l a a r r A A l l i i g g n n m m e e n n t t the telescope. The declin ation drift method requires star tells you how far away the polar axis is pointing from clination drift is simple and straight-fo rward, it requires a reat deal of time [...]

28 A A l l i i g g n n i i n n g g t t h h e e R R . . A A . . S S e e t t t t i i n n g g C C i i r r c c l l e e aps (#93722) or consultin g a current astronomy m agazine. nd easy to look up. 3. o e field. If not, find it and center it. 4. 5. rdinates o f the star. 6. t with the R.A. indicator (the zero mark on the ve rnier ly. If the circle does[...]

29 8. ipping in R.A. The telescope will track in R.A. as 9. d the object should be there. For some of the fainter objects, you may not be W you can “star hop” throug h the fi This process can be repeat e d for any given ni g ht . U U s s i i n n g g t t h h e e R R . . A A . . V V e e r r n ni Lock the R.A. clamp to preven t the telescope from [...]

30 With your telescope set up, you are read y to use it for observing. This secti on covers visual observing hints for both lar system and deep sky objects as well as general obs erving conditions which will affect your abili ty to observe. so O O b b s s e e r r v v i i n n g g t t h h e e M M o o o o n n eat o in g s. Often, it is tempting to loo[...]

31 O O b b s s e e r r v v i i n n g g t t h h e e S S u u n n Although overlooked by many amateur astronomers, solar obser vation is both rewarding and fun. However, because e Sun is so bright, special precautions must be taken when observing our st ar so as not to damage your eyes or your lescope. ever project an image of the Sun thr ough the tel[...]

S S e e e e i i n n g g ity of the atmosphere and d i rectly affects the amount of fine detail seen in extended s vary from time-to-time and place-to-place. The size of the air parcels compared to your aperture eeing conditions refers to th e stabil S objects. The air in our atmosphere acts as a lens which bends and distorts inco min g light rays. [...]

After looking at the night sky for a while you may want to try photographing it. Several form s of photography are possible with your telescope, including terr estrial and celestial ph otography. Both of these are discussed in moderate detail with enough information to get you started. Topics in clud e the accessories required a nd some simple tech[...]

34 4. e infinity setting. 5. he telescope s o that it poi nts in that 6. 7. 8. . Set the shutter speed to the “B” setting and focus the lens to th Locate the area of the sky that you want to phot ograph and move t direction. Find a suitable guide star in t h e telescope eyepiece field of view. This is relatively easy since you can search a wide[...]

35 • Any 100 to 400 ISO co lor slide film . Focus the telescope by turning the focus knob until the image is sharp. 4. 5. . Advance the film and repeat the process . Lunar Phase ISO 100 ISO 200 ISO 400 • Fuji Su per HG 400 2. Center the M oon in the field of y our telesco pe. 3 Set the shutter speed to the appropriate setting (see table 7-1). T[...]

36 desired target in the viewfinder of your camera. s possible. 5. Wait for the vibration caused b y releasing the shutter to diminish . Also, wait for a moment of good seeing. e telescope for the duration of th e exposure (see accompan y ing table). Replace the bl e fro telescop 8. Close the cam . Advance the film a are ready fo next expos t forge[...]

37 ith an illuminated reticle to monitor your guide star. For this purpose, Celestron offers the M icro Guide Eyepiece using and shu tter data. polar aligning, se e the Polar Alignment sec tion earlier in th e manual. . Remove all vis ual accessories . . Thread the Radi al Guider onto your telescop e. . Thread the T-Ri ng onto the Radial Guider. . [...]

CCD CCD I I m m a a g g i i n n g g f f o o r r D D e e e e p p S S k k y y O O b b j j e e c c t t s s pecial cameras have been de veloped for taking images of deep sk y images. These have evolved over the last sev eral ateurs can ta ke fantastic images. Severa l books have been written on ow to get the best images possible. The technology continu[...]

Whil s a t its be C C a a e your telescope requ ires little maintenan ce, there are a few things to remember that will ensure your telescop e perform st. Each optical design type has speci al collimation instructio ns described below. r r e e a a n n d d C C l l e e a a n n i i n n g g o o f f t t h h e e O O p p t t i i c c s s Occa n the objectiv[...]

Figure 7-2 similar to the diffraction Pick a bright star and center it in the field of the telescope. Study the image of the star while r acking it in and out of foc us using focus pattern is present, then collimat ion is ear as a concentr ic ring pattern simi lar to is approximately polar al igned r pointed at a stationary star without the motor d[...]

Before you begin the collim ation process, be sure that your te lescope is in thermal equ ilibrium with the surroundings. Allow 4 5 minutes for the t elescope to reac h equilibrium if you move betw een large tempera ture extremes. To verify collimation , view a star near the zenith. Use a me dium to high power ocular — 12mm to 6mm focal length. I[...]

42 C C The ng) the ce. Poo rror is th e three rews, placed 120 degrees apart, at the end of the telesc ope tube. The se condar y mirror (the small, elliptical mirror nder the focuser, in the front of the tube) also has thre e adjustment screws. To determine if your telescope need s ollimation first point your telescop e toward a bright wall or blue[...]

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Night Time Star Collimating After successfully completing dayti me collimatio n, night time star collimation can be done by closely adjusting t he prim ary mirror whil e the tele scope tube is on its m ount and pointing at a br ight star. The telescope shoul d be set up at night a n d a star's image should be studied at m edium to high powe r [...]

Figure 7-8 A collimated telescope should appear as a symmetrical ring pattern similar to the diffraction disk seen here. Take note of t he direction t he light appears to flare. For exam ple, if it appears to flare toward the thr ee o'clock pos ition in the fie ld of view, t hen you must m ove whichever screw or combination of collimation scre[...]

You will find that additional accessories for your Omni te lescope will enhanc e your viewing pleasure and expand the usefulness of your telescope. F or ease of referen ce, all the acces sories are listed in alphab e tical order. This is just a shor t listing of various ac cessories and pleas e visit the Celestron website for complete and det ailed[...]

Diagonal 2" Mirror (# 93519) - Celestron offers a 2" 90° Mirror Diagonal to slides into the barrel o f a 2" refractor focuser. This diagonal includes multicoated mirror and sm ooth mechanics th at are precision m anufactured for Digital Camera Adapter – Univeral ( # 93626) – A universal mounting platfor thread on Schmidt- Casseg[...]

48 e mount and therefore, its own T- Ring. Celestron has 8 diff erent models for 35mm cameras. which ce ts y y SkyScout ( # 93970) – A hand held personal planetarium that identifies and locates objects in the night sky. 6,000 object database with audio descriptions of over 200 popular objects. Comes with earphones, carr ying case and strap, SD ca[...]

A A p p p p e e n n d d i i x x A A T T e e c c h h n n i i c c a a l l S S p p e e c c i i f f i i c c a a t t i i o o n n s s Omni XLT Series 21088 21090 31057 11084 Omni XLT 102 Omni XLT 120 Omni XLT 150 Omni XLT 127 O segrain ptical Design Refracto r Refractor Newtonian Schmidt- Cas Aperture 102mm (4.0") 120mm (4.7 ") 150mm (6.0"[...]

A A p p p p e e n n d d i i x x B B - - G G l l o o s s s s a a r r y y o o f f T T e e r r m m s s A - Abs The apparent mag at a star wou it were obser a standard di 10 parsecs, or 32.6 li olut Sun e o would just be visible lear m y . Air isk The apparent si ze f a star's disk produced even b y a perfect optical system . Since the s r be focu[...]

Focal length The distance between a l ens (or mirror) a brought to focus. The focal length divid e nd the point at whi c h the image of an object at inf inity is d by the aperture of the mirror or lens is termed the focal ratio. J - ets r (LY) m/ sec. the light-year e quals a distance of 9 .46 X 1 trillion km (5.87 X 1 estial body. The brightest st[...]

Resolution The minimu m detectable angl e an optical system can d etect. Beca use of diffraction, th ere is a limit to the minimum angle , resolution. The l arger the aperture, the bett er the resolution. T he ang Right Ascension: (RA) ular distance of a celes tial object measured in hours, minutes, and seconds along the elestial Equator eastward f[...]

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C C e e l l e e s s t t r r o o n n T T w w o o Y Y e e a a r r W W a a r r r r a a n n t t y y A. Celestron warrants this telescope to be free from defects in materials and work ma nship for two years. Celestron will repa ir or replace such product or part thereof which, upon inspe ction by Celestron, is found t o be defective in materials or work[...]

Celestron 283 Torr Tel. Fax 310) 212-5835 Copy All rights reserved. (Products or instructions may change with tem # 21088-INST rin 5 Columbia Street nce, CA 90503 U.S.A. a (310) 328-9560 . ( Web site at http//www.celestron.com right 2 007 Celestr o n out notice or ob ligation.) I P ted in China $10.00 01-07[...]