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How to Drift Align


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Drift alignment is easily the most accurate method of polar aligning. I’ve tried polar alignment scopes, computer based imaging programs, and simply using a compass, but nothing short of a good drift alignment is good enough for the demands of imaging in particular.

However until a kind person in the past showed me this method I couldn’t get the hang of it – I never could figure out which way was north or south or east or west in an eyepiece. It changed with scope type, usage of a star diagonal or straight though, simple or compound scope.

I take no credit for this method, and can’t remember who taught it to me, but it has proven easy to remember and simple to use by the people I’ve passed it on to. Since I’ve had a great deal of pleasure reading cloudy nights for years, I thought I’d contribute by passing this on.

All that’s needed is an illuminated reticule eyepiece, and a scope with an RA drive.

The method works equally easily in both the Northern and Southern Hemisphere, however as I’ve never been to the Northern Hemisphere I can’t truly vouch for the truth of this!

1          Rough polar align.

Azimuth Adjustment Southern Hemisphere

2.         Point scope at a star near the meridian with a declination close to zero

3.         Turn reticule eyepiece until the stars motion (with the drive turned off) is parallel to one of the lines in the eyepiece

4.         Align star on the reticule line and turn on the motor

5.         As star drifts off reticule, correct by use of the drift rules below

drift this direction drift this direction
   
^ ^
thumb thumb
left palm facing you right palm facing you
push star this way >>> push star this way <<<
   
Newtonian Refractor with star diagonal
Straight through refractor Cassegrain with star diagonal
Straigh through cassegrain  
2 reflections 3 reflections

Azimuth Adjustment Northern Hemisphere

2.         Point scope at a star near the meridian with a declination close to zero

3.         Turn reticule eyepiece until the stars motion (with the drive turned off) is parallel to one of the lines in the eyepiece

4.         Align star on the reticule line and turn on the motor

5.         As star drifts off reticule, correct by use of the drift rules below

 

drift this direction drift this direction
   
^ ^
thumb thumb
right palm facing you left palm facing you
push star this way <<< push star this way >>>
   
Newtonian Refractor with star diagonal
Straight through refractor Cassegrain with star diagonal
Straigh through cassegrain  
2 reflections 3 reflections

Altitude

2.         Point scope at a star 20 degrees above horizon near due east or due west and with a declination close to zero

3.         Turn reticule eyepiece until the stars motion (with the drive turned off) is parallel to one of the lines in the eyepiece

4.         Align star on the reticule line and turn on the motor

5.         As star drifts off reticule, correct by use of the drift rules below

If star is in the east, push the star in the opposite direction to the drift

If star is in the west push the star in the same direction it is drifting

I hope this helps and makes it easier to master the art of drift alignment!

Cheers

Gary McKenzie

Melbourne, Australia




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