OK... I'm starting to second-guess myself on my collimation results with an ST80. Hopefully, someone here can give me some insight.
Firstly, diffraction patterns are good. Nice, airy disk, symmetrical rings, etc. However, racking from focus to inside focus then outside focus sometimes shows the original focus point to be slightly off-center.
It's hard to describe without a visual aid, but imagine a star that's perfectly in focus. When you rack out of focus, you expect the center of the diffraction ring to originate from the center of the star, with the diffraction rings growing concentrically outward. What I sometimes observe is the center of the diffraction ring originates not from where the star's center should be, but off to the side. The inside of the airy disc is clean, and uniform. And the two out most concentric rings are clearly delineated.
Still, I get nice airy disk with no signs of visible coma or astigmatism.
Suggestions?
Thanks,
James
Firstly, diffraction patterns are good. Nice, airy disk, symmetrical rings, etc. However, racking from focus to inside focus then outside focus sometimes shows the original focus point to be slightly off-center.
It's hard to describe without a visual aid, but imagine a star that's perfectly in focus. When you rack out of focus, you expect the center of the diffraction ring to originate from the center of the star, with the diffraction rings growing concentrically outward. What I sometimes observe is the center of the diffraction ring originates not from where the star's center should be, but off to the side. The inside of the airy disc is clean, and uniform. And the two out most concentric rings are clearly delineated.
Still, I get nice airy disk with no signs of visible coma or astigmatism.
Suggestions?
Thanks,
James
Regards,
James
[SIZE="Small"]
[COLOR="Blue"]Toys: [COLOR="Red"]2006 Evolution MR, 2005 BMW M3, Meade LX200R[/COLOR][/COLOR][/SIZE]
