Re: Reciprocating

Thanks to Guillermo, Guy et al for the info on recip failure. I had shot a wonderful
pic of xmas-lit barns on my first pinhole roll, just taking a reading and then
figuring 'well, 4x exposure plus a little bit ought to do it.' Then, I got nervous,
and sent in my question. According to the answers, I was anywhere from 1/3 to 2/3
stop under, but there were lights AND snow in the scene, so I processed normally.
And, voila', a perfect exposure. So again thanks and 2 questions: How is the formula
derived and what, exactly, is the sunny 16 rule?

Cheers,

Stephen Harris