8 Second versus 240 Second Exposures All Other Parameters Being The Same

Experiment as part of a proof of concept to make film exposures that could last for weeks. The long exposure (on the right) had the exact same setup as the shorter exposure (left) including the use of the same filter and fstop. The 8 second exposure was determined by my light-meter as correct for the r72 filter needed to filter out most of the light.

It  has very little to do with the film both sides were developed in same batch. More about that later if I decide to build a special camera. Also if I used a low reciprocity film like Neopan 100 I'm sure I could get exposure times of a year.

I'm looking at the ultra long exposure work of Michael Wesely and thinking how I might do it without necessarily duplicating his methods as referenced in this thread 

I'm making use of the fact that at really short exposures time very little light actually falls on the film. Plus reciprocity failure happens the same for short exposures as it does for long exposures as film needs more than one photon withing a certain period to expose a grain.

A 2 hour exposure could have been achieved except for the fact of the bitter cold arctic weather made it too difficult to stand around on a street corner. The baby steps were enough to lead me to believe a month would be no problem while a year is possible but will add some more difficulties. It would be interesting to put an auto shutter on my large format pinhole camera.

Note: it was really really cold and I couldn't get my tripod to lock down solid, so there is some tripod caused camera shake.