Fixing sensor tilt and collimation

[barx1963]

I am fairly certain I have some minor tilt and collimation issues on my current 8" Edge and ASI1600 combo. I have CCD Inspector that hopefully will assist with fixing this. Question is, is it better to fix one before the other or is it a case of running through a few iterations to reduce error to acceptable levels?

[RyanJones]

Hi Malcom,

My personal approach would be to address collimation first as it is done on axis. Slight tilt will have little effect in the center of the image so it can be taken care of independently. Once the collimation is corrected the tilt can be corrected separately as you will know the aberrations in the outer field are due to the remaining tilt and nothing else ( barring under/over correction ). I could be wrong but that would be my approach and justification.

Cheers

Ryan

[barx1963]

Thanks Ryan
That was my guess! just curious if ayone has practical experience.
Thaks again.

Malcolm

[The_bluester]

With my SCT, I did collimation first and tilt second. Most of the apparent tilt came down to collimation.


Metaguide might be a help for collimation.

[barx1963]

Cool. Thanks Paul. Have both Metaguide and CCD Inspector so will swing both at the problem.

Malcolm

[Joshua Bunn]

Hi malcolm,


Do you have a rotator in the image path or any way to accurately rotate the camera?

[barx1963]

Yes I do. Moonlite Litecrawler focuser.

Malcolm

[Joshua Bunn]

great, and maybe you already know this, but,

A little test you can do to distinguish between tilt and collimation... Tilt will show up as the star elongation not changing relative to the sensor no matter where you rotate the camera to. With mis-collimation, the star elongation will change relative to the sensor when you rotate the camera. I know this isn't what you were asking, but it can help to know if one or the other is giving issues, allowing you to move onto the next.


Josh

[barx1963]

Josh. Thank you so much, not sure why I hadn't thought of that myself!!

Malcolm

[Andy01]

If you do find there's a tilt problem, contact Diego at Sidereal trading. He's got a laser bench setup that did wonders for my sensor tilt issue. :)

[barx1963]

Thanks Andy. Will do.

Malcolm