Quote:

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If anyone needs a scaled drawing of the one I made up let me know. I can try it out with your particular focal length and see if it scales properly.

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Some common sizes that I'm sure a lot of folks will be interested in.

2032mm fl, 200mm diameter (8 inch sct f/10)
1280mm fl, 200mm diameter (8 inch sct with .63 reducer)
4064mm fl, 200mm diameter (8 inch sct, 2x barlow, for planetary stuff)
585mm fl, 80mm diameter (Williams zs80)
1540mm fl, 127mm diameter (orion apex 127)
400mm fl, 80mm diameter (orion st80, common guidescope)

Ok, that covers most of what we have here

But this does bring up the interesting question. Will I still get useable diffraction spikes in all of the 8 inch configurations, from a single mask, or, does it really need the different spacings on different focal lenghts ?

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