Quote:
Originally Posted by Paul Haese
I am going to get adapters made up so I can use my Atlas focuser on the scope and that will narrow down where movement can take place.
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Interesting... good luck with the Atlas, hope it works out!
I think I might have narrowed down the problem. It may not be *the* problem, but it's certainly a problem.
If I put the autocollimator in the focuser drawtube and have the drawtube parallel to the ground, then apply some downward pressure to the drawtube (simulating load from the camera and other gear), the collimation clearly shifts.... looking through the offset pupil I can see the reflections "unstack" as I apply pressure. Looks like there's significant slop in the drawtube.
I've also noticed that I can "unstack" the images in the offset pupil of the autocollimator by:
- Wiggling the AC in the focuser; or
- Rotating the AC in the focuser; or
- Rotating the focuser itself
It's hard to know if it's collimated given the inconsistencies.
Anyway, last night before I discovered the above (which I noticed this morning), I got everything well collimated according to the offset pupil of the AC and the cheshire. I then attached the camera and captured the first image. You can see very bad tilt, which I think now is due to the weight of the imaging train screwing up the collimation.
Taking 15 second exposures and then analysing them in PixInsight's aberration inspector I was able to achieve the next image by making small adjustments to the focuser's collimation. Clearly still out of focus in one corner and poorly corrected in some areas, but much better than it had been. I assume I could have managed this by adjusting the secondary as well. The field illumination improved during this adjustment also. Sadly, this is still not usable and if I'm correct, it's going to shift out of collimation again as I point to different targets and gravity has varying impact on the drawtube. Not sure how I can resolve this... might send Moonlite an email and see if there's an adjustment I can make to reduce the slop in the drawtube.