Reading the submission guidelines indicates the images can be made with a digital pinhole, doesn't have to be film. I'm suspecting though that my lensbaby pinhole won't cut it.
Well I'm definitely going to look into it. My pinhole that I made a few months back gave me some good results and I still am curious about this format so I may just shoot something more compositionally thought out for this special day.
From the participation rules: The submitted photograph may be made by using any photographic material: film, paper, liquid emulsion, B&W, color, and any photographic process, including digital.
I took this last week for the balloon challenge. Done with my 5DmkII and pinhole body cap. One aspect I really like is the ability to use the crazy high ISOs for grain. This was taken at ISO 25600, allowed for a hand holdable exposure.
Earlier this afternoon I went to the Cantor Art Center on the Stanford University campus. In the contemporary art gallery they had on display a LARGE pinhole shot of Stanford; I think it was probably eight feet wide. It was a negative because the photographer had put the paper for the finished image into the camera! So what kind of camera can hold an eight-foot negative? The photographer used a large truck as the camera. There weren't many details about how he did it, but I imagine that he mounted a pinhole in one of the walls of the truck and tacked up the paper on the opposite wall. It did say that the exposure was "all day."
~~Dan
Edited to add:
I did a web search. The photographer is Shi Guorui. You can find out more at this site.