Hello, I'm a big fan of meridian lines inside churches and I know these are sort of camera obscura sundials.
While I understand the geometry behind pinhole camera projections I can't seem to find any help on how the solar image forms after the rays pass a sizeable aperture nodus (for example a vertical 25cm nodus projected onto a wall 10 meters away) and how the ratio of hole size vs. projection distance affects the size and fuzzyness of the final projected image. So what's the geometry behind that? PS: Some sources refer to the projected image as "stenopaic image". Is this universally acceptable? -- Dan-George Uza
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