It is a go. WooHoo. I have everything I need except the focal length. I want to use 5x7 paper for the negs and I want a fairly wide angle. WOuld seven inches be enough and still have the circle cover the paper or should I go closer to 9 inches for the focal length?
The links would be great. Thanks.
For 5X7 a FL of ~4" will give you about a 90° angle of view. Here's a link for a pinhole Forum .