If you have trouble focusing, rotate the focusing knob so the drawtube is in as far as it will go. Now look through the eyepiece while slowly rotating the focusing knob in the opposite direction. You should soon see the point at which focus is reached.
The thumb screw on the top of the body of the focuser (Figure
20)will lock the focuser drawtube in place once the telescope is properly focused. Before focusing, remember to first loosen this thumb screw. Do not loosen the thumb screw too much as there must be some tension to keep the drawtube secure within the focuser.
If you find the drawtube tension when focusing is either too tight (focus knob is difficult to turn) or too loose (image shifts when focusing), you can adjust it by tightening or loosen- ing the two drawtube tensioning set screws on the focuser. These are the two small set screws located on either side of the focus lock thumb screw. Adjusting these set screws requires a 1.5mm hex key.
Note About the Focuser Drawtube Lock Knob
The focusers of the SkyQuest XT12 IntelliScope feature a drawtube lock knob. There are times when you may want to lock the drawtube to preserve the focus setting (such as when using certain afocal photographic attachments). This is done by turning the focus lock knob (Figure 20) clockwise until it is tight. The focus setting will now be locked. When you need to adjust the focus again, be sure to loosen the lock knob.
Viewing with Eyeglasses
If you wear eyeglasses, you may be able to keep them on while you observe, if your eyepieces have 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, however, you may find images noticeably sharper with your glasses on.
Aligning the Finder Scope
The finder scope must be aligned accurately with the tele- scope for proper use. To align it, first aim the main telescope in the general direction of an object at least
-the top of a telephone pole, a chimney, etc. Position that object in the center of the telescope’s eyepiece.
The finder scope uses a
Note: The image in both the finder scope and the main telescope will appear
Now look through the finder scope. Ideally, the object should be within the field of view. If not then coarse adjustments to the alignment thumbscrews will be needed. Once the image
View through finder scope and telescope
Figure 30. The view through a standard finder scope and reflec- tor telescope is upside down. This is true for the SkyQuest XT12 Intelliscope and its finder scope as well.
is in the finder scope’s field of view, you will now use the align- ment thumbscrews to center the object on the intersection of the crosshairs. By loosening one alignment thumbscrew, you change the line of sight of the finder scope. Continue making adjustments to the alignment thumbscrews until the image in both the finder scope and the telescope’s eyepiece is exactly centered.
Check the alignment by moving the telescope to another object and fixing 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 until the two images match up.
The finder scope alignment should 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’s alignment thumb screws until the star or planet is also centered on the finder’s crosshairs. The finder scope is an invaluable tool for locating objects in the night sky.
Focusing the Finder Scope
The finder scope with your SkyQuest XT12 IntelliScope has adjustable focus. If the images in the finder appear somewhat out of focus, you will need to refocus the finder scope for your vision. Loosen the lock ring located behind the objective lens cell on the body of the finder scope (see Figure 19a). Back the lock ring off by a few turns, for now. Focus 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 be adjusted again.
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