next challenge Noise
Astrophotography Gear spring 2015. Paramount MyT mount supporting a At65EDQ refractor with a QSI 690 camera.
You wake up in the morning to see the sun rising in the east and go to bed after it has set in the west; Day in day out. We take it for granted. Or perhaps we don't like to think about the fact that we are standing on a rock in space that is spinning at 1000 miles per hour. This spinning is the first challenge facing an astrophotographer. When you take a picture of the night sky using a camera on a fixed tripod the stars smear as the earth rotates. It's like trying to take a picture of someone running by. They end up a blur in your picture. If you want to capture a sharp picture of the runner you might pan the camera in the direction they are moving, cancelling out their movement relative to your camera. It's the same with the stars. You can place your camera on a motorized tripod that moves in the exact opposite direction and speed of the earth's rotation, cancelling out the movement of the stars. There are many flavors of these specialized tripods called "mounts." In the end the key to getting long exposures of the night sky is that the axis of rotation of these mounts must point exactly at the pole of our night sky and it must rotate at the same rate in the opposite direction as our earth. Thankfully these mounts don't need to rotate at 1000 miles per hour! It is similar to when you are driving in a car and look out the window at the passing scenery. Objects close to the car speed by in a blur, where objects far away move much more slowly. For astrophotography the objects are extremely far away and so they appear to move much more slowly than the 1000 miles per hour that our earth rotates on its axis. This rate of rotation is known as sidereal. To take long exposures of the universe from earth you need to track your camera across the sky at this rate.
I've explored many ways of meeting this challenge and I’m currently moving my optical gear using a Software Bisque Paramount MyT mount (the red machine in the picture). It provides me with very precise sidereal tracking corrected for atmospheric refraction and full computer control.