I quickly found other sites. And it short order was staring at the input form of the mask calculator at the AstroJargon web site. I ran some trials and viewed the output SVG files in Visio. And then found myself in a quandary. What do I use for the aperture, in mm, for a camera lens? And what should I use for the structural bar thicknesses? Should I play with the 'Bahtinov factor' and what should I set it to? I ended up with some strange looking masks.
Steve Richards, on helpful his Bahtinov mask page, said that he changed the 'slot width override' to reduce cutting. And he showed another version with a short cylindrical tube to permit fitting the mask over the telescope or lens. A good idea.
It was in the Stargazers Lounge and Cloudy Nights sites that I found threads specifically on making masks for a camera lens. Still, I could not seem to find one clear rule or guideline. So I decided to wing it.
I designed a small mask in Visio with a 40mm opening. Each slot (or bar) was 2mm in width. I figured I could cut this size of slot with scissors without too much trouble. Really didn't know what do to with the structural bars so left them at 5mm.
Suddenly realised I could simplify the cutting if I grouped together components and built it in layers. And positioned everything inside an open circle. Ha. Super easy.
Printed the template. Cut out the pieces. Glued the elements into the circle. Set up the false star and took a look through the view finder.
Well, definitely, the light was being diffracted. But I did not see the familiar six-pointed pattern. It was this blobby thing. It worked mind you. I could tell the focus was improving or getting worse. But without the long spike moving into the cross, I was not sure when I was at perfect focus.
I suspected the problem was a combination of the thickness of the slots and the extreme thickness of the structural bars. I wondered if I could truly cut thinner slots...
Will have to do more research.
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