World Pinhole Photography Day or What I was going to submit.

[Rodex]

The interesting thing about this image, is that it took 9 HOURS to expose! A problem with reciprocity of the Tri-X 320 film I was using.

Jon

How did you find out what the exposure time was?

[jon.oman]

How did you find out what the exposure time was?

I found this link:

http://pinhole.stanford.edu/equations.html

Towards the bottom of the page is "Reciprocity Calculations". I used the one for Tri-X.

With the formula in hand, I wrote a small Java program to generate an exposure chart. The chart contains the indicated (metered) exposure (1 second, 2 seconds, etc.) and the reciprocity exposure time.

Jon