Image train calibration

SCT Corrector plate

The hyperstar needs the corrector plate to be centered. Center the corrector plate using a phone on a tripod. Remove the secondary mirror, and place the cameraphone on a tripod away from the scope. Line it up and adjust it till everything is centered. If you do this well and there are still elongated stars in one corner -- always the same corner of the image regardless of the camera rotation -- then you have camera tilt, and need to adjust that out as well. 

Tilt

Last night I was able to dial in the camera tilt quite a bit. It's not perfect, but it's a lot better. I did this without any software analyzing the photos. I just used a bahtinov mask. I did this with my refactor, but once it's adjusted the tilt should be good for any scope. 

1) Using a bahtinov mask adjust the BF while looking at a live feed of images. After each BF adjustment focus a center star, and check the stars at the edges. When it's out, the center will be focused, and the edges will be out. Bring it in as close as possible.

2) Adjust the tilt:

While (not_done)

a) adjust one of the three tilt screw sets.

b) set the live feed to 1s exposure

c) focus the center star

d) set the live feed to 30s exposure

e) check the focus of the edges.

i) If it's worse backoff the adjustment.

ii) If it's good enough not_done = false

end while

Here's two shots I saved. It started out quite a bit worse, but I didn't save any of those photos. You can see the focus on the left improves in one of these shots.

https://photos.app.goo.gl/93gcUhA2w9GXjoJ9A

The out-of-focus pattern is exactly the same regardless of camera rotation, so this is not image train tilt, it's camera tilt.