Mechanism Explanation in short:
For the star tracking mode, the Rotator will track continuously, so theoretically during the exposure time the star is relatively still with the lens.
For timelapse mode, it will move step by step in an increments manner, it will move only after the exposure, so during the exposure time, the object is relatively still with the camera lens.
Below is the explanation in detail
For Star Tracking Mode:
GAUDA: In this mode, the tracker is keeping moving 360 degrees in 24 hours. It's NOT moving in a move shoot move manner in star tracking mode.
As the earth rotates 360 degrees in 24 hours, (relatively we can say the star is moving in the opposite direction, the same speed as earth), so without the tracker, the star tail happens.
With the help of the tracker (it rotates in the opposite direction with the earth), theoretically, your camera will keep aiming at the same star (the star is still for the camera), then we can shoot with longer exposure.
How to do polar alignment ?
We know that the earth has self-rotation, Extending its rotation axis, you will find it goes through the Polaris in the Northern Hemisphere.
Imagine the earth is a rotating plate(as the image in left below shown), Our rotator will be another rotating plate stand on the earth. In order to counteract the rotation of the earth, our Rotator has to Rotates with the same Axis as the earth.
That means, our rotator’s rotating axis should go through the Polaris. Where is the Rotator’s rotation axis? The laser pointer is vertical to the Rotatoer’s surface, then the laser beam will be parallel to the Rotator’s rotation axis.
So from now on, we just make sure below 2 things:
- The laser is vertical to the Rotator’s surface, so we can take the laser as the Rotation axis (parallel).
- Let the laser beam goes through the Polaris, that’s to say align the laser beam with the Polaris.