Let’s track the stars!
Hey, Today I’m going to talk about a project I made some time ago. If you like photography and astronomy then you will love this.
If we were to watch the stars for a length of time, we would appreciate that they are constantly moving. This phenomenon is caused by the Earth’s rotation around its axis. An equatorial mount is a machine which has a rotation axis that is Polar aligned. This is useful, for example, when making long astrophotographical exposures because it allows photographs to be taken minus the star trails and when making observations through a telescope, the stars or objects that are being looked at do not go out of the field of vision.
Waht I did is nothing new; this small world is super researched, there are tens of configuartions and designs to create a good tracker (to move the càmera as the stars move). What I did is called a type 4 double-arm barn-door tracker. The arm is moved by using a stepped motor to minimize errors, but it could also be done by using a handle.
After getting plans and material, you should make a sketch of the cuts for the wood board, and make sure, before joining anything, that everything is correct. When cutting the board, the different lengths (r, b and c) don’t need to be precise. In fact, if you can have a margin it’s better, because you can correct any constructive error. After, you can cut the hinge, it should be the same length as the board you are going to attach it to. You may also need to cut the screw: if so, do it at the length you think you will use, but remember the indications given here are done with a M6 300mm long screw. The different pieces can then be assembled. Remember that now, it is important to keep the lengths precise and the hinges must be parallel.
When joining the screw to the drive arm, you will see that it is difficult to place the screw because of the hinge, however a solution was found on the internet which inspired me to do this.
Thanks to a webpage by Stephen Tonkin where the importance of the friction between the pieces of wood is explained, I created this solution with all the parts which were made of metal.
To calculate how long the right plate had to be, I calculated the measurement of the distance between the hinge of the drive arm and the drill, at Ѳ=0º and Ѳ=54º (5 hours tracking), and calculated the difference. The final solution was created to allow the drive screw to incline freely as it became longer. When joining the viewfinder to the base board, remember it must be parallel to the hinges . The head can be placed anywhere on the camera arm.