Quote:
Originally Posted by Stonius
I take it that since the airy disk requires point sources, this little trick wouldn't tease out any more detail in planetary observations?
Best
Markus
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The square aperture could help Bojan get in close to a bright star by redirecting the diffraction pattern in such a way that he may be able to place the low brightness star in a niche where there isn't much unwanted bright star energy.
A graded apodizing mask may apparently also help in close to a bright star by actually reducing the total amount of diffracted energy (at the expense of a broader central point) - and it will improve planetary contrast if used with a biggish scope. However, looks like a simple graded mask may not help all that much with a large central obstruction - the square aperture should be useful though.
From
https://www.telescope-optics.net/apodizing_mask.htm
"The two main opposing effects of this type of pupil apodizing are:
(1) improved contrast transfer for larger details, but decreased for those close to the limit of resolution, and
(2) impaired limiting stellar resolution, but improved resolution of unequal doubles with much fainter companion in the area of the first bright rings of the brighter principal star.
Bojan, a square aperture will redirect the diffraction into a strong cross shape - if that pattern could be aligned to lie behind your crosshairs you may have a neat solution.
Cheers Ray