Maximum negative size vs. Aperture vs. focal length?
I want to make a wide-angle pinhole for solargraphs. I have read about a plan for a matchbox pinhole that has an angle of view of about 160 degrees and I wanted to achieve that same range of view, but be able to use 8x10 BW photo paper. If I made a camera with a focal length of about 6-15mm, would I be able to achieve a similar angle of view without an unholy amount of vignetting? Is there a specific formula to find out the maximum negative size in proportion to the focal length and pinhole size before vignetting occurs?