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Center dot - black or white?

Started by jacobson, 09/05/2006 07:22AM
Posted 09/05/2006 07:22AM Opening Post
I always assumed that the center dot "doughnut" on a Newtonian primary mirror should be black to avoid scattered light. Recently I was at a presentation where the speaker said it should be white. He didn't give any reason. Maybe white is more visible during collimation. Any advice?
Posted 09/05/2006 10:25AM #1
White is easier to see. This just makes collimation quicker. The center spot is shaddowed by the secondary, so scatter should not be a problem.
I use the red reflective triangles from Jim Fly myself.

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