Last updated: 23 December 2004

Subject:	Some Technical Tips: "Radioactive" focusing aid
Sent:	Wednesday, December 22, 2004 02:10:27
From:	Mr. Tom (MrTomsMail@gmx.net)
here is a picture for your Some Technical Tips area:

"Radioactive" focusing aid

This cardboard made focusing device for my Celestron 9 has 3 triangle
shaped holes, pointing towards the SC middle axis. So all in all it
looks a bit like a radioactivity sign. It has 3 advantages:

- 3 wholes means more light than 1 or 2 holes
- 3 objects are easier to overlay than 2 (and their dancing looks funny ...)
- in focus you can even fine-focus because of the 6 spikes around a star,
  due to the triangle-shaped holes

Hartmann Mask
Try it yourself ! Cheers, Tom

Mike here: For more on the usefulness of the Hartmann Mask see the article '"Hartmann Mask" Focusing Aid'.

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