Sunday, July 31, 2016

made a 2" occulting eyepiece

Uncle Tony and I have been wanting to build an occulting eyepiece from a long time.

I showed him my prepared violet filter, with straight smooth edge. He produced an old Meade 1¼" eyepiece. We took it apart. This revealed, unfortunately, that the inner diameter of the ocular tube, at the field stop position, was much smaller than 1¼. We didn't relish the idea of reducing the size of the brittle filter.

2" eyepiece with occulting foil at field stop

Tony returned with a different eyepiece. And old 2" with a highly accessible field stop in the removeable shaft. I suggested we try building a super-simple barrier. Tony agreed. I grabbed some aluminum tape, cut a small piece, traced around the shaft for the curve, and cut within it. Taped it on the field stop baffle. Done!

I wondered, as did others, if the shiny metal will cause reflections. I proposed we could paint it black.

We were excited to use it...

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