I have three collimation tools- a Farpoint Cheshire, laser, and Catseye Autocollimator.
The scope in question is a BIG 12" F4 imaging newtonian, which means that it is an on equatorial mount and the focuser points downwards to minimize center of gravity.
The primary mirror cell is not that great, so I need to check collimation before every session.
The problem is that I can not get consistent alignment with the laser due to the focuser and its thumbscrews. The only consistent way is zero thumbscrews while pressing the laser against the lip of the drawtube. None of the permutations of one thumbscrew, two thumbscrews, tighten one first, barely tighten them, tighten while pressing against the drawtube, etc give a consistent result.
On the other hand, the tilting problem doesn't affect the Cheshire since that only has to do with lateral displacement, which is small. I can leave it clamped with the thumbscrews and adjust the primary mirror back and forth.
It's very hard to use the AC because I have to look from underneath the scope and can't really adjust the secondary at the same time.
Finally, my coma corrector / camera combo does seem to have some tolerance to tilt if it is not pointed exactly along the optical axis, as I use this with good results on one of my other scopes, also with thumbscrews on the drawtube.
With that long intro out of the way, the question is this: Assume I can get the cheshire (primary) collimation spot on. And then I put the laser or AC in the draw tube, and wriggle it around, and find that for SOME orientation, it is spot on. Does that mean that this telescope now makes a perfect image plane, even if it may not be exactly perpendicular with the drawtube, and probably won't be exactly the same as the camera's optical axis? From the perspective of the camera sensor, it might be a little offset from the ideal image plane (not that big of a deal) and barely tilted (maybe the coma corrector's design is tolerant of this?).