Orion XT8 CLASSIC manual

INSTRUCTION MANUAL IN 165 Rev . D 05/08 Providing Exceptional Consumer Optical Products Since 1975 Customer Support (800)676-1343 E-mail: support@telescope.com Corporate Offices (831) 763-7000 89 Hangar Wa y , W atsonville, CA 95076 Orion ® SkyQuest XT6 Classic, XT8 Classic & XT10 Classic Dobsonian Reflecting T elescopes Orio n T e lesc opes.c[...]

Secondar y mirror with 4-v ane spider (not shown) Right side panel F ront brace Eyepiece Rac k (optional) Handle T op baseplate Ground baseplate 2 Figure 1. The SkyQuest XT Dobsonian (XT6 pictured) EZ Finder II Eyepiece F ocus knob Optical tube Altitude side bearing CorrecT ension F riction Optimization System Pull loop Left side panel[...]

T able of Contents 1. Unpacking ............................. 3 2. Assembly ............................. 4 3. Using Y our T elescope .................... 7 4. Collimation (Aligning the Mirrors) .......... 10 5. Astronomical Obser ving ................. 12 6. Care and Maintenance .................. 16 7. Specifications ......................... 17 [...]

4 2. Assembly Now that y ou have unpac ked the bo xes and f amiliar ized y our- self with all the par ts in front of y ou, it’ s time to begin assemb ly . The optics of the telescope are already installed in the tube, so most of the required assembly concerns the Dobsonian base. Assembly of the Dobsonian Base Ref er to Figure 2 during base assemb[...]

5 Once in the cradle, the tube should pivot freely up and down with gentle hand pressure. Note that the tube will not yet be proper ly balanced, since the ey epiece and EZ Finder II are not in place, and the CorrecT ension system has not been installed. 9. The rubber bumper (L) provides a conv enient “stop” f or the telescope’ s altitude moti[...]

6 used under dark skies and a bright setting is used under light- polluted skies or da ylight. At the end of your obser ving session, be sure to tur n the power knob counterclockwise until it clicks off. When the white dots on the EZ Finder II’ s body and po wer knob are lined up, the EZ Finder II is turned off. Installing the CorrecT ension (XT)[...]

7 The CorrecT ension system is now installed and engaged. If you wish to remov e the telescope from the base, you will first need to disconnect the spr ings from the “posts” on the Dobsonian base. The springs will remain captive on the alti - tude side bearings, so they will not get lost. Inserting an Eyepiece The final step in the assemb ly pr[...]

which will lock the f ocuser drawtube in place once the tele - scope is properly focused. If you find the drawtube tension when f ocusing is either too tight (f ocus knob is difficult to tur n) or too loose (image shifts when focusing or drawtube mov es inward by itself), the ten - sion can be adjusted f or optimal performance. On the XT8 & XT1[...]

more light-collecting area, or aper ture, can yield higher mag- nifications than a smaller aper ture telescope. The maximum pract ical magnification for any telesco pe, regardless of optical design, is about 60x per inch of aperture. This tr anslates to about 360x f or the SkyQuest XT6 and 480x for the XT8. K eep in mind that as magnification is in[...]

ali gnmen t is importan t to ensur e the peak perf ormanc e of you r telescope, so it should be check ed regularly . Collimation is rela - tively easy to do and can be done in da ylight. T o chec k collimat ion, remo ve the ey epiece and look down the f ocuser drawtube . Y ou should see the secondar y mirror centered in the drawtube , as w ell as t[...]

possible . It may not be perfectly centered, b ut that is OK. Now tighten the three small alignment scre ws equally to secure the secondar y mirror in that position. If the entire primar y mirror ref lec tion is n ot v isi ble in t he s eco nda r y mi rro r , a s in F igu re 13c, you will need to adjust the tilt of the secondar y mirror. This is do[...]

12 the image with the focusing knob . If the telescope is correctly collimated, the expanding disk should be a perfect circle (F igu re 18). If the image is unsymmetrical, the scope is out of collimation. The dar k shadow cast by the secondar y mirror should appear in the v er y center of the out-of-focus circle , like the hole in a donut. If the ?[...]

13 matter . Y our eyes tak e about 30 minutes to reach perhaps 80% of their full dar k-adapted sensitivity . Many obser vers notice improv ements after sev eral hours of total dar kness. As your ey es become dar k-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 yo[...]

14 shadows f all on the craters and canyon walls to give them defi- nition. While the full moon may look like a tempting target, it is not optimal f or viewing! The light is too br ight and surface definition is low . Even at par tial phases the Moon is very bright. Use of an optional Moon filter to helps to dim the glare. It simply threads onto th[...]

est deep-sky objects, first catalogued about 200 years ago by the F rench 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 visib[...]

16 rors, the better . Small specks of dust or flecks of paint hav e vir tually no effect on the visual perf ormance of the telescope. The large pr imary mirror and the elliptical secondar y mirror of your telescope are front-surface aluminized and ov ercoated with hard silicon dioxide, which prev ents the aluminum from o xidizing. These coatings no[...]

17 SkyQuest XT 10" Primar y mirror f ocal length: 1200mm Primar y mirror diameter : 254mm, BK7 optical glass F ocal Ratio: f/4.7 F ocuser : Cra yford, accepts 2" and 1.25" ey epieces with included adapter , collimatible Optical tube material: Rolled steel Eyepiece: 25mm Sirius Plössl, fully coated with multi-coatings, 1.25" bar[...]

18 One-Y ear Limited W arranty This Orion SkyQuest XT telescope is warr anted against defects in materials or wor kmanship f or a period of one year from the date of purchase. This w arranty is for the benefit of the original retail purchaser only . During this warranty per iod Orion T elescopes & Binoculars will repair or replace, at Orion’ [...]