HELP!!
I just finished building a wide field refractor from a cooke triplet (96mm f/4.1) and a star test shows a tight pinpoint on Rigel, but I have this dim circle of light around the star, off center, filling half the field!
I can't completely center the star in this circle of light, moving the focuser around only helps slightly, but the circle remains...
When de-focusing in, the star shows a nice concentric circle, but de-focusing out, the star scatters, and disappears!
I have throughly baffled the short tube with black velvet, and I can see no internal reflections...a laser in the diagonal comes out the center of the front lens.
Is it possible that one of the three elements have shifted?
Please forgive my ignorance...what I don't know about refractors can fill a book!
CB
I just finished building a wide field refractor from a cooke triplet (96mm f/4.1) and a star test shows a tight pinpoint on Rigel, but I have this dim circle of light around the star, off center, filling half the field!
I can't completely center the star in this circle of light, moving the focuser around only helps slightly, but the circle remains...
When de-focusing in, the star shows a nice concentric circle, but de-focusing out, the star scatters, and disappears!
I have throughly baffled the short tube with black velvet, and I can see no internal reflections...a laser in the diagonal comes out the center of the front lens.
Is it possible that one of the three elements have shifted?
Please forgive my ignorance...what I don't know about refractors can fill a book!
CB
There's something on the Moon! 8O
