This tool can help to get a good collimation for the telescope optic.
This is for use with reflector telescope, astrograph refractor must only be adjusted by the manufacturer.
Before any attempt with this procedure you must carefully read the telescope documentation, Beware that doing it wrong can make the secondary mirror to fall on the primary.
To start, point the telescope to a bright star, then select the menu Tools → Collimation.
Click the Center button.
This start a preview exposure loop. Center the star in the bull eye, defocus enough to see the concentric ring in the image, adjust the exposure time so the image is not overexposed but high enough to mitigate the seeing fluctuation.
When ready click the Start button.
This crop the image to the size defined for the focus window and draw concentric circle centered on the star.
You can adjust the Number of circles so they match the main ring in the star image.
Now adjust slowly the telescope collimation screw to make the ring concentric.
Always go by small touch because every adjustment move the position of the star. The program try to automatically follow the star by modifying the camera ROI.
But the collimation must be done with the star at the center of the field, so periodically click the Center button to recenter the star in the bull eye then the Start button to continue the adjustment.
If no circle are draw after you click the Start button this is probably because the focus window is to small for the size of the defocused star. In this case refocus a bit to make the star circle smaller or increase the size of the focus window.