Hi RodShea, Sunday, April 1, 2007, 12:38:00 AM, you wrote: R> I have a red 635 nm laser... R> lens or negative achromatic doublet.. Regardless of anything else Rod, you don't need an Achromat on a Monochromatic light source. Go on, kick yourself :) -- Best regards, Richard in the UK _______________________________________________ ATM mailing list http://www.atmlist.net/