Focusing a telescope is important DUH. But when you take images, especially long exposure images, it is critical.
Focusing can be done by pointing your telescope to a distant star or planet, and focus your telescope manually until you are happy with the result.
Or you use a little tool called a Bathinov mask. If you have a 3D printer, you do not even have to buy one, you can print one yourself! Just make sure you get one that matches the size of your telescope aperture.
How does it work
This is how you use a Bathinov mask:
- Point your telescope to a distant bright star or a planet
- Fix the Bathinov mask to your telescope
- Look through an eyepiece or a camera and you’ll notice that the image is distorted and instead of a star, you’ll see a cross and a straight light through it
- Fine-tune the focus till the straight line goes exactly through the middle of the cross.
- If you use a camera, do not forget to zoom in, to see the image a lot bigger. It will allow you to focus more precisely, for much more focus accuracy
It is as easy as that.
