background image

 

Celestial Equator

Horizon

W

S

N

Zenith

Polaris

 

Meridian

your North–South 

line in the sky

Line up 

the Polar Axis 

E

This angle

is the same 

as your latitude

90

ϒ

fro

m p

ole t

o equa

tor

ϒ

9

can easily be kept within the telescope’s field of view. 
In the Northern Hemisphere, the Earth’s rotational axis points very close to the 

star Polaris, the North Star. This can be easily be demonstrated by pointing at 

Polaris with your index finger, and after several minutes the sky will have rotated 

from its original position around your finger. When the RA axis is pointed at 

Polaris, the telescope can follow the path of the stars as they rotate around their 

rotational axis. 
There are several methods of aligning the RA axis to the Earth’s rotational axis; 

the quickest and easiest method is to align the RA axis to Polaris. This will keep 

celestial objects centered in the telescope’s field of view over time with adjust-

ments to the RA slow motion control cable. Swing the optical tube of the telescope 

about the declination (DEC) axis so that the tube is parallel to the RA axis. The 

DEC setting circle should read +90. Move the tripod so that the RA axis roughly 

lines up with Polaris. Adjust the latitude (tilt) of the RA axis up and down until 

Polaris is in the center of the field of the finder scope; center Polaris in the cross-

hairs. Then, with the 25mm eyepiece in the focuser,repeat the process of adjusting 

the tilt of the RA axis so that Polaris is in the center of the field in the 25mm 

eyepiece. Using the T-knob on the side of the mount, lock down your latitude 

position . . . this should not have to be adjusted again unless it comes loose or you 

go to an observing site several hours North or South of your main site. 
Moving the telescope from object to object is accomplished by loosening the RA 

and DEC axes locking mechanisms and moving the telescope into the general 

area you wish to observe. Lock down the axes by tightening the knobs and locate 

the object using the slow motion cables. Moving the tripod is not necessary. To 

keep the object in the field of view of the telescope over a period of time, use the 

RA slow motion control to keep the object centered. You are moving the RA axis 

to follow the sidereal motion of the object around the rotational axis of the Earth. 

tube Balancing

Balancing the optical tube to the mount’s two axes of rotation is critical for the 

equatorial mount to operate smoothly. If unbalanced, there will be torque put on 

one axis of the mount, and the telescope will tend to shift at the most awkward 

moment so the heavier end will be lower than the lighter end. 
To balance your telescope, set the mount so the DEC setting circle reads +90. 

Rotate the telescope in RA until the counterweight is on one side of the mount 

and the tube on the other. Leave the RA lock knob loose so the telescope will 

rotate freely in the RA axis. Adjust the counterweight so when horizontal, the 

telescope does not rotate in RA, and then tighten the RA lock knob. You will  

now want to release the DEC axis lock knob and slide the optical tube forwards 

and back in the cradle rings until there is no torque in the DEC axis. Now the 

telescope is completely balanced and will not move without being touched, 

regardless of the axes being locked down. 

8

bearing surface by scratching it up. 
To carry the telescope out of the house for at-home viewing, you can easily carry 

the tube and base separately. Use common sense when moving the telescope.  

While the components are not terribly heavy, they are bulky; use caution to avoid 

hurting yourself. If in doubt, get someone to help you. 

Field use and set-up

When selecting a location for observing, be sure to place the telescope as far away 

as possible from direct artificial light, such as street lights, porch lights, and auto-

mobile headlights. The glare from these lights will seriously impair your night 

vision. The telescope should be located on a relatively level surface for proper 

operation of the mount. You may set it on a sturdy level platform to increase the 

height of the eyepiece, but be sure it’s strong enough and does not wobble. 

tracking an object

When viewing the night sky, celestial objects will drift out of the telescope’s field 

of view due to the rotation of the Earth. Equatorial mounts, like the one that 

comes standard with the SkyView, are designed to compensate for this problem. 

When aligned correctly with the rotational axis of the Earth, the right assention 

(RA) axis of the telescope will match the Earth’s rotation and the celestial objects 

Polar Alignment

Summary of Contents for SkyView 90mm

Page 1: ...I n s t r u c t i o n M a n u a l Orion SkyView 90mm Equatorial Refractor Telescope P O Box 1815 Santa Cruz CA 95061...

Page 2: ...e 15 9 Specifications 17 3 2 1 Introduction Important Points About Your New Telescope Take the time to read this instruction manual thoroughly so that you may gain the maximum benefits from your new t...

Page 3: ...The overall effect is that the observer can track the heavens along the path of the Earth s rotation Finder Scope Aids in pointing the telescope It is a small low power telescope with cross hairs that...

Page 4: ...oad the telescope into your car for a trip to the hills Common sense prevails as long as the telescope doesn t roll or bounce around you won t hurt it at all by moving it Naturally you should be caref...

Page 5: ...are moving the RA axis to follow the sidereal motion of the object around the rotational axis of the Earth Tube Balancing Balancing the optical tube to the mount s two axes of rotation is critical for...

Page 6: ...more detail You may want to try using more powerful optional eyepieces for observing the details of the moon s surface 10 6 Observing Tips Techniques Seeing Limitations Atmospheric conditions vary sig...

Page 7: ...tive to each other the positions of each planet are constantly changing Don t be disappointed that you can t tour all the visible planets when your first get your telescope you must limit yourself to...

Page 8: ...tics Any quality Optical lens cleaning tissue and Optical lens cleaning fluid spe cifically designed for multi coated optics can be used to clean the exposed lenses of your eyepieces or finder scope N...

Page 9: ...instrument which proves to be defec tive provided it is returned postage paid to Orion Warranty Repair 89 Hangar Way Watsonville CA 95076 Proof of purchase such as a copy of the original invoice is r...

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