The mechanism behind Move Shoot Move star tracker:
We know our earth rotates once every 23h 56m4s. Its rotation axis goes through the Polaris. (almost), stars are not stationary relative to our earth.
Just as the below photo shows, the stars circle around the Polaris.
According to 500rule, we usually couldn't exposure more than 25s, most often less than15 seconds. This leads to:
1. Many faint stars are missing from our photo.
2, Ugly stars trails.
3, The noise ruins our composition.
- How to expose more than 60 seconds?
Move Shoot Move tracker rotates at the same speed as the Earth, just in the opposite direction. Then the stars will be tracked, and they will stay in the view. Your exposure time can be up to minutes, and The missing faint stars will show up in your pictures, star trails will disappear, lower ISO helps to solve the noise. Finally, you can get clear, pinpoint photos of stars and the night sky.
Earth's rotation axis goes through the Polaris. (almost, check the above blue earth)
So, we need to make the Rotator's rotational axis parallel to the Earth's rotation axis. This is called polar alignment.
- Is your Polar alignment difficult and complicated?
I don't know RA, D-dec, and I've never played astronomy? Can I do polar alignment?
Don't worry, it's easy-
- If you already know where to find the Polaris, then just aim the laser at the Polaris, then polar alignment is done😉.
- If you don't know where to find the Polaris, then download one free app, 'Skysafari,' set it to VR mode. It will spot the Polaris when you move your phone around the sky.
- How to do a polar alignment in Southern Hemisphere?
- If the star is tracked, will the foreground be blurred?
Yes, the foreground will be blurred. Then how? We change the shooting sequence.
- First, we set the tracker OFF to get the clear foreground(your composition).
- Then we wait for the ideal stars to show up in our composition, turn the track ON, shoot the tracked stars. Then combine these two pictures to get the final one.