
Collimation Screws | Viewfinder |
| Eyepiece |
Viewfinder
Bracket
Fig. 14: Viewfinder Alignment.
Important Note: Objects appear
This image inversion is of no consequence when observ- ing astronomical objects, and in fact all astronomical telescopes yield inverted images.
During terrestrial observing, where a
Note that for Schmidt- Newtonian models, no means of image inversion is available; while these tele- scopes may be used for ter- restrial observing, the image will not be correctly oriented in either
tending to drift down in either direction. Then
3.Achromatic refractor and
The telescope is now properly balanced on both axes. Next, the viewfinder must be aligned.
Aligning the Viewfinder
The wide field of view of the telescope's viewfinder4,( Fig. 1a) provides an easier way to initially sight objects than the main telescope's eyepiece 3,( Fig. 1a), which has a much narrower field of view. If you have not already attached the viewfinder to the tel- escope tube assembly, follow the procedure described in step 9, page 12.
In order for the viewfinder to be useful, it must be aligned to the main telescope, so that both the viewfinder and telescope's optical tube 10,( Fig. 1a) point at the same position in the sky. This alignment makes it easier to find objects: First locate an object in the
To align the viewfinder, perform steps 1 through 4 during the daytime; perform step 5 at night. Both the 6 x 30mm and the 8 x 50mm viewfinders align in an identical man- ner. Refer to Fig. 14.
1.Remove the dust covers from the optical tube (9, Fig. 1a) and the viewfinder.
2.If you have not already done so, insert the
3.Look through the viewfinder eyepiece at an object at least
4.Unlock the R.A. lock (33, Fig. 1d) and the Dec lock (17, Fig. 1d) so that the tel- escope turns freely on both axes. Then point the main telescope at a tall, well- defined and stationary land object (e.g., the top of a telephone pole) at least 200 yards distant and center the object in the telescope's eyepiece. Focus the image by turning the focus knobs (8, Fig. 1b). Retighten the R.A. and Dec. locks.
5.Look through the viewfinder and loosen or tighten, as appropriate, one or more of the viewfinder collimation thumbscrews (5, Fig. 1b) until the viewfinder’s crosshairs are precisely centered on the object you previously centered in the main telescope's eyepiece. You are now ready to make your first observations with your telescope.
NEVER point the telescope directly at or near the Sun at any time! Observing the Sun, even for the smallest fraction of a second, will result in instant and irreversible eye damage, as well as physical damage to the telescope itself.
5.Check this alignment on a celestial object, such as a bright star or the Moon, and make any necessary refinements, using the method outlined above in steps 3 and 4.
With this alignment performed, objects first located in the
Choosing an Eyepiece
A telescope’s eyepiece magnifies the image formed by the telescope’s main optics. Each eyepiece has a focal length, expressed in millimeters, or “mm.” The smaller the focal length, the higher the magnification. For example, an eyepiece with a focal length of 9mm has a higher magnification than an eyepiece with a focal length of 26mm.
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