That was my instinct, Guillermo, and thanks for your
answer.
Funny thing is, I tried it yesterday at a minute and a
half--my rough calculation, which was close to your
suggested 84.5 seconds--and it completely overexposed
the film. It was all white (using Polaroid Type 55).
Then I tried it
I built my first (and only pinhole camera at this point) around a 2 x 3
Grafmatic back and enjoy using it very much. I too whish I had seen the
website before taking the thing apart to find out how it works! I was able
to straighten a few bent septums using a six inch steel ruler and gently
