The Web contains a considerable amount of resources explaining drift alignment. You are highly encouraged to Google these and read them all. This article will give you a compact summary of what you need to do. It is a handy printout that you can carry with you to the field. Now, let’s begin…
What do you need?
You need a reticle:
Perform initial alignment mentioned in parts 1 and 2 of this article making sure mount is level and close to North. Using a polar scope will bring you very close to Polaris. It is crucial to make sure your mount is level.
(I) Align your reticle with the East-West direction
Stars, as the sun do, appear to move from East to West. You need to align your reticle to this East-West direction. How to do this? Simple, with your tracking motor turned off watch a star moves on your field of view and rotate the reticle such that it is aligned with the path of the star. With this you caught two birds with one stone:
You can also find the North-South directions by simply putting your hand or your flash light on the North side of the opening of the OTA, the reticle to the same side of your hand/flashlight is north and the opposite side is south.
(II) Adjusting Polar Axis Azimuth
To adjust the Polar Axis Azimuth (an East-West adjustment), we’ll follow these steps:
Now, use your mount control to adjust the East-West pointing of the polar axis until you get rid of this North-South drift. Notice that the star can drift East-west as well due to RA error. Ignore this as it will be taken care of by the tracking (and Auto guide if you have it).
(III) Adjusting Polar Axis Altitude
This is the up-down tilt of the polar axis. To adjust it, follow the following steps:
Now use your mount controls to adjust the altitude until you eliminate the North-South drift.
You may need to repeat this process to fine tune your polar axis pointing until you reach the point where your object stay in place for as long as your exposure time will be. Now you are ready for astrophotography!