Discovery Sky T76 с книгой [13/56] Focusing

Optical nderscope assembly and alignment

Unthread two screws in the back of the telescope tube. Place the nderscope base above the holes on

the tube. Lock the nderscope base into position by tightening the screws (g. 3).

Optical nderscopes are very useful accessories. When they are correctly aligned with the telescope,

objects can be quickly located and brought to the center of the view. Turn the scope end in and out to

adjust focus (g. 6).

To align the nderscope, choose a distant object that is at least 550 yards (500 meters) away and point

the telescope at the object. Adjust the telescope so that the object is in the center of the view in

your eyepiece. Check the nderscope to see if the object is also centered on the crosshairs. Use three

adjustment screws to center the nderscope crosshairs on the object.

Focusing

Slowly rotate the focus knobs one way or the other until the image in the eyepiece is sharp. The image

usually has to be nely refocused over time due to small variations caused by temperature changes,

exures, etc. Refocusing is almost always necessary when you change an eyepiece, add or remove a

Barlow lens.

Operating the mount

The AZ mount is an alt-azimuth mount that allows you to rotate the telescope about the vertical and

horizontal axes and change its altitude and azimuth. Due to Earth’s movement, the objects will be

constantly shifting out of your view, so you will have to adjust the altitude and azimuth of your telescope

to continue your observations.

Reference materials usually list declination coordinates in degrees, hours and minutes above or below

the horizon line. Azimuth coordinates may sometimes be listed with the compass points (N, SW, ENE,

etc.), but it is more commonly listed in degrees around the 360-deg plane, where north is 0°, east is

90°, etc. (g. 7).