I have a question that I can not figure out for the life of me. When shooting with my home made pinhole camera that takes an 8x10 negative, I always get this weird 45 (roughly) degree area of brightness towards the bottom of the image and it lasts for about 1/4 of the picture length. It doesn't start on the bottom left corner or bottom right, but it's sort of in the middle. Here are some links to demonstrate what I'm talking about. I'm not sure whether I like this effect or not, if its something I want to fix, or if it can be fixed at all. Any ideas as to what could be causing this would be greatly appreciated - thanks.
Just occurred to me -could it be a "lens" flare?