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Old 29-06-2010, 06:19 PM
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sheeny (Al)
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sheeny is offline
Join Date: Jun 2005
Location: Oberon NSW
Posts: 12,780
Thumbs up Al's Focus Aid is here!

Allan Gould has done it again! He's an ideas man is our Al!

I got another PM today asking for a focus aid to help focus with the bahtinov mask focus aid... who'd have thunk it? An aid for aid! Definitely an ideas man!

Anyway here's my interpretation of what I think Al wanted.

I'm interested to hear how successful this turns out to be. I found a couple of examples where it is pretty obvious the thing is in focus or very near to it, but I can see that it might still be pretty subjective in poor seeing.

Procedure to use:

1. Position the little cross hairs at the centre on the intersection of the diffraction spikes.
2. Rotate the centreline reticle to coincide with the central diffraction spike (and fine adjust position).
3. Adjust width of gauge lines until the angled diffraction spikes intersect the gauge lines on a tick mark.

If the star is in focus the diagonally opposite tick mark will be on th same diffraction spike at the same time.

Note: if your Bahtinov Mask is not perfectly symmetrical, each diagonal pair may coincide with the tick marks at different gauge widths.

How much room is left for icons on your desktop, Paul?


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