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I don't see diffraction rings ( "Airy discs" ) at all

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#26 Asbytec

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Posted 02 August 2021 - 05:12 AM

Yeah, I can see the rings when out of focus


But not in focus, right? At high power?

#27 Buqibu

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Posted 02 August 2021 - 07:03 AM

Yeah, so when out of focus the star is a big circle with rings radiating from the centre, when in focus its a point of light at low mag, a smudgy blob at high power, no airy disc to be seen. One thing I did notice was when removing the diagonal, it got very slightly sharper, maybe a tad brighter. Still no disc but it seemed promising, I'll keep trying on nights of good seeing away from buildings. Thanks for the help so far
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#28 RichA

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Posted 02 August 2021 - 07:46 AM

I have a barlow and a Celestron Zoom. I've gone up to 165x, still just a smudge. Could be the seeing, could be the scope. Anyway I appriciate the help. I've also tried without the diagonal, same story.

You have a balcony, take seeing out of the equation.  Try to find an artificial light source of reasonable brightness but very small size and aim the scope at that.  In order to be a point source and not a visible light, it has to be far enough away or the glint of the sun off a chrome car bumper or insulator on a power pole can sometimes provide an infinitely small but bright image.  You will need at least 200x to get a clear look at the diffiraction image.




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