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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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