[ATM] Ultimate Collimation

[johncdeitz@comcast.net]

Hello Rien: You write-

You have to be quite sure about the center though.
Is there a good way to find it?

On small mirrors, say to 8 or 10in I simply use a disc of paper with the proper opening at the center. For larger mirrors I take two slats of wood with length greater than radius and with the two pieces held firmly together I drill one hole near one end, going through both pieces and then another hole, again going through both pieces, at the radius. I drop a nail through one hole and then separate the two arms oy 90 degrees or so and drop longer nails through each of the two holes. You now have a jig that when the two outboard nails are up against the rim of the mirror the center nails marks the center. Don't hesitate to remove other center marks (o-rings, etc.) as these may give problem with sighting the reflections.
John

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