Interesting technique Mike. Did you try it in color? There is a technique on this web site for digital cameras that I want to try as soon as I get an extra camera body cap. Check it out here

www.pcworld.com/article/id,132090/article.html

Never heard of the pin hole effect,does it have a literal meaning,as if looking through a pin hole?I will have to do some research on this effect.Interesting.