Quote:
Originally Posted by jerry3672
Dennis- Good point! The more edges you have the more diffraction you get. However as our friends in Russia have found also too many slots will blur the spikes and make it a bit more difficult to focus. Pavels formula is designed to catch the peak of each light wave and stack them on top of each other to get the maximum diffraction spike that is clear. Farmer Dave posted his mask generator that works fabulously.
When I sat down and plotted a curve for different focal ratio scopes I saw a curve in the results. I drew a straight line down the middle and came up with a simple formula that works on every scope we tested. These were as small as an ED80mm up to a 16 inch Meade LX200. From F4 to F15. 26 different scopes so far. All of the work with the following math:
Aperture divided by 35 will give you the spacing for a center cutout and 8 up and 8 down. The other tip we did was when you get down less than 130mm we added one extra slot on the angled side only. this helped the spikes to show up a bit brighter.
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Hi Jerry
Thanks again for providing your insights and some experimental results from the research and development efforts of developing the mask for commercial release.
Not withstanding Pavel Bahtinov’s original talent, intuition and generosity in publishing his design, I think you have been very generous in providing guidance and helpful information on several forums that I have enjoyed visiting on this topic.
I note that your posts have provided encouragement for others to better understand the principles involved, as well as providing helpful “nudges” to the army of DIY mask makers, helping them focus on the key design issues for optimising their own home made designs.
I hope that once the home made masks begin to un-stick, wilt and fall apart, their owners will visit your website and purchase the “last a lifetime” model! I feel certain I’ll be one of those after our next humid summer season down under!
Cheers
Dennis