Finderscope Alignment; The Altazimuth Mount; About Magnification - National Geographic NG70FS Owner's Manual

F A
INDERSCOPE LIGNMENT
Since a telescope has a narrow field of view by design, it can be challenging to locate a
particular star or planet. For this reason the telescope is fitted with a low-power, wide-
field miniature telescope called a finderscope. Always use your finderscope to locate
the object you want to view FIRST. The finderscope should be aligned with the
main telescope tube before you begin using the telescope, in order that both
scopes are positioned to always provide exactly the same angle and view.
Note: Objects in the finderscope are upside down. This is normal and is common to all
astronomical telescopes.
Complete the following settings in daylight:
1) Insert the 20-mm eyepiece into the prism. Look at an easily recognizable, stationary object that is at least 90
metres away. Slightly loosen the handle of the pan and tilt arm. Move the telescope tube until the object is in
the centre of the field of view. Then bring the image into focus.
2) Firmly retighten the handle of the pan and tilt arm so that the telescope is locked in position.
3) Look through the finderscope. If the object is not visible or centred in the finderscope, simply release one of
the three small adjusting screws holding the finderscope and reposition the finderscope until the object is
centred within the X-shaped crosshairs.
4) All screws should be completely tightened as soon as the view through the finderscope coincides with the
view of the main telescope.
5) You may need to repeat this procedure to ensure a perfect alignment.
T A M
HE LTAZIMUTH OUNT
The NG70FS telescope is fitted with an altazimuth mount. "Alt" refers to altitude, the vertical movement of the
telescope, while "azimuth" refers to the horizontal movement.
To change the angle of the telescope's optical tube, simply loosen the handle of the tilt arm. Adjust the position
of the optical tube and re-tighten the handle of the tilt arm.
To change the horizontal direction of the telescope tube, loosen the horizontal adjustment lock, move the
telescope tube, and re-tighten the horizontal motion lock (See Fig. 2).
A M
BOUT AGNIFICATION
The magnification power of a telescope indicates how much an image is enlarged or how big and close it
appears to the viewer. The focal length of the eyepiece, combined with the focal length of the telescope,
determines the magnification power. To calculate the power of your telescope with any particular eyepiece,
simply divide the focal length of the telescope (300-mm) by the focal length of the eyepiece (indicated in "mm"
on the eyepiece collar).
Example: 300-mm focal length (tube)
20-mm focal length (eyepiece)
The 3X Barlow lens and interchangeable eyepieces provide the following magnification:
Eyepiece
20-mm
4-mm
= 15X magnification power
Power Power With 3X Barlow Lens
15X 45X
75X 225X
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