Dennis,
I like this focusing mask thanks for the links and info. I'll try to make one like you've pictured, but first I may use the diffraction angles you've given on a mask like this...LINK I've been experimenting with the three holed Hartman mask and I think breaking up the symmetry with diffraction spikes like you've described will make it more useful.
Regards,
-------------------- Matt
Apogee 50mm BB scope
ETX-60 BB
Meade 70-az
5" DIY Newt (wip)
C6-N on CG-4 GEM
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