This 'pin-roll' image is from a tubular pinhole camera made in
about 20 minutes, earlier today. Basically, it is the size of
an (empty) toilet roll of cardboard approx. 1 1/2" x 4". (38mmx100mm).
As it so happens, a sheet of 4x5 film curls up just perfectly inside this cylinder.

I made a pinhole (actually a bit too big) with a 1/32" drill (.78mm) and
taped it in the middle of the long side of the roll (not at an end).
The focal length is about 38mm, and the aperture is about f48.
The film is of course held in a tightly curved arc inside the roll.

I placed the 'pin-roll' camera on the floor, and exposed for 30 rhinoceroses. ;-)

There are some weird distortions from this 12.5mm lens equivalent
for a 35mm camera. The ceiling fan in the first room made some
funky ghosts, and there are lots of reflections on the floor. I believe
that the two horizontal lines are actually reflections internally off the edges
of the tightly curled sheet of 'celluloid' sheet film.

PS. June 15. I have been told (by someone with excellent pinhole and engineering credentials)
that the horizontal lines are almost certainly the actual film reflecting back onto itself.
He has told me that this is somewhat common when the film is so tightly curved it
is also almost completing a full circle (except for space for the pinhole).