I think I was getting to much reflection off of the metal that the pinhole is in. So I blacken the metal. I seems to have improved the picture quality somewhat.
here are a couple the latest pictures taht I took with my Nikon D50. I changed the focal length of the pinhole by adding about 1 1/2 inch tube to the body cap and putting the pinhole at the end of the ube. It doesn't seem like it has improved the picture sharpness at all (in fact it seems more blurry).
Here are 5 of my latest pinhole images taken with my large pinhole camera. I'm still working on getting the exposure right.
btw the plane is the seaplane that appeared in the Raiders of the Lost Ark movie. It is at the Western Aerospace Museum near the Oakland Airport. You can take a tour of the plane and sit where Indiana Jones sat.