Originally posted by kai_in_paisley the fact that, beyond 1sec exposures, films become 'less sensitive' and need extended exposure times or adjusted aperture.
Depends on the film. Ilford films are all one second. Kodak is generally two seconds on their slow-to-medium films. Fuji Acros is 120 seconds (yes, two minutes) before reciprocity failure begins.
Originally posted by kai_in_paisley I assume that the auto-exposure on the LX doesn't compensate for this by itself ?
I believe that to be correct. Some advanced cameras do, I think, compensate for reciprocity failure. Typically, people who shoot long enough exposures where reciprocity failure occurs will be able to also calculate the reciprocity failure compensation.
I'll be taking my LX on a two-week trip (starting next week) and a big part of that is astrophotography. So watch the Forum front page in December for the next installment of the Astrohotography Series for a bunch of long-exposure film shots using the LX.