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Old 01-02-2017, 09:42 AM
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Thumbs up 3D-printable Spikes Eliminator

I found this thingy when looking for something else:
http://www.thingiverse.com/thing:1260926

It could be quite useful... printing this ASAP

Last edited by bojan; 01-02-2017 at 09:59 AM.
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Old 01-02-2017, 10:00 AM
JA
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Hi Bojan,

I find diffraction spikes very distracting even in the most beautiful astro images. It would be great if this broke them up effectively.

I could see how it certainly might have some prospect of some effect by presumably not reinforcing the artifact so much by varying the spider width and breaking up the interference pattern that essentially is the spike. I'd love to see some images with/without. It's on my to do list to make a reflector one day with a simple one or two leg spider, so that sort of design could be really useful, so thanks for sharing.

Best
JA
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Old 01-02-2017, 09:22 PM
Wavytone
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Poor idea IMHO. A curved vane spider will be better than that.

Firstly it's quite feasible to make entirely adequate curved 1 or 2 vane secondary supports and if you really must, 3 vanes, using bent metal and hand tools. And probably quicker than 3D printing.

The area obstructed by the secondary matters - including the vanes - in that this redistributes energy from the central spot in the Airy pattern, and puts more energy in the rings. In this respect that frankly sucks, in my stepdaughters language.

Just because you can make something with minimal effort (3D printing falls into this category) doesn't mean it's a particularly good idea.
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Old 01-02-2017, 09:46 PM
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Levitate the secondary on 4 magnets ... no spikes. Of course not sure you coud procure strong enough neodymium magnets or electromagnets...and keeping the secondary aligned may be problematic (though vectoring would help).

Or...hmmm...use a refractor
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Old 01-02-2017, 09:56 PM
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Easier - use a flat glass plate to support the secondary, plane parallel to 1/4 wave or better and anti-reflection coated ...

Might be easier to pinch a corrector plate from an old SCT... then you could use a spherical primary as well ...
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Old 01-02-2017, 09:59 PM
Wavytone
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Easier - use a flat glass plate to support the secondary, plane parallel to 1/4 wave or better and antibreflection coated ...

Might be easier to pinch a corrector plate from an old SCT... then you could use a spherical primary as well ...

But wait a minute ... this is the whole point of maksutov newtonians - no spider vanes so no spikes at all, all spherical surfaces, fast aperture, no coma and a sealed optical tube to keep dust out ...
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Old 02-02-2017, 06:14 AM
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Guys.... let's be practical here.
The cost of this mask (could be cut out of black paper as well) can't possibly be compared to the price of (multi-coated) glass plate, supporting the secondary... or levitation gadget .
The provided link on abovementioned webpage explains this in more detail: http://serge.bertorello.free.fr/antiaigr/antiaigr.html
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