I spent a few hours last night getting the mirror alignment just right on the telescope. It’s an excruciating task.
Once your close to collimated, you only make very tiny adjustments to the secondary mirror collimation bolts, so I take an image of an area of the sky that has lots of stars, inspect the image and make another adjustment if necessary. It’s all too easy to go too far and throw it way out again.
The star I chose was Alpha Cassiopeia also named Schedar, as it would give me stars from corner to corner. Here’s the final image after collimation.