Dec. lock lever
Dec. setting circle
Front opening
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Azimuth adjustment knobs (2)
Figure 7. The Atlas EQ Mount.
R.A. setting circle
R.A. lock lever
Polar axis finder scope
Latitude scale
Latitude adjustment
3a). 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 finderscope body. Precise focusing will be achieved by focusing the finder scope on a bright star. Once the image appears sharp, retighten the locking ring behind the objective lens cell. The finder scope’s focus should not need to be adjusted again.
Magnification & Eyepieces
Magnification, or power, is determined by the focal length of the telescope and the focal length of the eyepiece. Therefore, by using eyepieces of different focal lengths, the resultant magnification can be varied.
Magnification is calculated as follows:
Telescope Focal Length (mm) = Magnification
Eyepiece Focal Length (mm)
The Atlas 10 EQ has a focal length of 1200mm, which when used with the supplied 25mm eyepiece yields a magnification of:
1000mm = 40x
25mm
The magnification provided by the 10mm eyepiece is:
Always start with your lowest power eyepiece and work your way up. Start by centering the object being viewed in the 25mm eyepiece. Then you may want to increase the magnifi- cation to get a closer view. If the object is
Using 2" eyepieces
The Atlas 8 EQ’s focuser is capable of accepting optional 2" eyepieces. To use 2" eyepieces you must remove the 1.25" adapter from the focuser by loosening the two thumbscrews that hold it in place (Figure 4). Once this adapter is removed, insert a 2" eyepiece into the focuser and use the same thumb- screws to secure the larger eyepiece.
6. Setting Up and Using the |
1000mm
10mm
= 100x
Equatorial Mount |
The maximum attainable magnification for a telescope is direct- ly related to how much light it can gather. The larger the aper- ture, the more magnification is possible. In general a figure of 60x per inch of aperture is the maximum attainable for most tel- escopes. Your Atlas 8 EQ has an aperture of 8 inches, so the maximum magnification would be about 480x. This level of magnification assumes you have ideal conditions for viewing.
Keep in mind that as you increase magnification, the brightness of the object viewed will decrease; this is an inherent principle of the laws of physics 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!
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 7) is designed to compensate for that motion, allowing you to easi- ly “track” the movement of astronomical objects, thereby keep- ing them from drifting out of your 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 the built in motor drive. But first the R.A. axis of the mount must be aligned with the Earth’s rotational (polar) axis— a process called polar alignment.
7