Two nights ago storms rolled in over Jinyun Mountain and I caught this lighting bolt striking somewhere in the distance across the Jialing River. Looks like its hitting Xi Shan Ping where the prison is, and given the relatively short time between the bolt and the thunder, I would say that's about right.
Thanks to Ralf Pergandé XPan.se I now know why our pinhole photographs haven't been turning out. (see the photos taken by my wife below and at www.bei-ga.com) The Shanghai film that we have been using--that people rave about for its quality and low price-- is plagued with severe reciprocity failure. Our second trip to photograph Song Dynasty rock sculptures ended again with blown out highlights due to extremely long exposures needed to expose the shaded areas of the subject.
Basically the way it works is that anything in bright sunlight gets by with a short exposure time--2 to 10 seconds with our wooden cameras. The shadow areas should need an exposure of around 20-40 seconds, but the longer the exposure time, the less sensitive the film is to light. Ordinarily, this doesn't start to happen until the expsure becomes longer than 1 minute. But with the Shanghai film we're using, it happens fast and extreem so that 45 seconds becomes 6 minutes. It's manageable except when there are light areas in the photo---even a ray of sunlight coming through the trees becomes completely burned out.
Ralf suggested Acros for minimal r.f. problems. I can get it here, but for 8 times the cost compared with Shanghai film. Eek!