Last time when I'm taking images of the sun, I found need I need to re-focus after taking images for 10 minutes or something like that, the OTA under direct sunlight, will expand and cause the focus position to change.
Now, I wonder if the collimation need to be fine tuned as well? It seems logical to say yes.
However, it's next to impossible to do with the sun, since an ERF is installed in the front, and it blocks the collimation screws.
So, maybe collimation at night time is the only way to go.