★
↑
★
↑
E
W
S
N
E
W
S
N
N
★
↑
★
↑
★
★
★
★
↑
☆
North
South
Inverted View
East
Move to
east in
azimuth.
West
E
W
S
N
E
W
S
North
South
Inverted View
East
West
★
★
★
☆
↓
★
South side of the sky
South side of the sky
(NCP)
R.A.axis
Move to
east in
azimuth.
(NCP)
R.A.axis
Chapter 5 APPLICATION
Drift Alignment in the Northern Hemisphere
East
West
North
South
★
・
・
・
・
・
West
East
North
South
★
・
・
・
・
・
East
West
South
North
★
・
・
・
・
・
(Inverted View)
(Erect View)
(Mirror-Reverse View)
Precise Polar Alignment (Drift Alignment)
Look for south
in the sky
1
2
If you align the mount with the provided polar alignment scope correctly, the mount will be able maintain tracking celestial objects within
the field of view of your telescope's eyepiece. For astrophotography, it enables you to take exposures of 5 to 10 minutes with a telephoto
lens of 200mm focal length or less.
However, if you want to take longer exposures than 10 minutes or use a telephoto lens of longer focal length than 200mm, more precise
polar alignment is required. The following method of polar adjustment will be done by watching the movement of a bright star in the
eyepiece and it is called drift alignment.
Align the mount to the north celestial pole by using the polar alignment scope. This will save time during the process of drift alignment.
Align the Mount in the direction of Azimuth.
Prepare an eyepiece with cross hairs reticle (illuminated). Choose a bright star near the celestial equator and near the meridian, and
put it in the filed of view of the eyepiece. Turn off the power switch of the mount momentarily while looking into the eyepiece to see
which direction the star moves. Confirm the west and rotate the eyepiece so that one of the cross hairs is parallel to the east-west
direction in the field of view.
The figure shows the directions of north, south, east and west in the eyepiece according to a type of your telescope with or without a star diagonal.
The following descriptions are based on a refracting telescope without a star diagonal. Drive the mount at sidereal rate and look into the eyepiece
to monitor the drift motion of the star in the north-south direction.
If the star drifts north (i.e. It moves down apparently due to inverted view), move the mount to east in azimuth.
If the star drifts south (i.e. It moves up apparently due to inverted view), move the mount to west in azimuth.
Adjust the mount with the azimuth adjustment screws. Make appropriate adjustments to the polar axis to eliminate the drift.
Note:
Refrain from doing the star alignment with the STAR BOOK TEN if you need to perform the drift alignment. If the mount type is chosen
as "Equatorial mount without polar setting", the position information collected by the star alignment will be applied for the polar
alignment. This will spoil the drift alignment as any drifts from the celestial pole are detected and corrected automatically. Choose
"Equatorial mount with polar setting" to avoid these corrections. Also turn off the function of depressing atmospheric refractions.
Note:
You may find that the star in the field of view moves slightly in the north-south direction, but ignore it at this stage and continue the adjustments.
66