Re: A final thought about reciprocity failure with paper negs.

on 30/11/01 12:34 pm, Bill Erickson at erickson@hickorytech.net wrote:

The more I thought about this the more I realized that, with very long
exposures, the risk of overexposure is lessened by reciprocity failure, and
the longer the exposure, the less the overexposure risk. In essence, it is
far easier to fatally underexpose than fatally overexpose, and far more
efficient to overexpose and then work backward from that than vice versa.

I find that reciprocity failure is not a problem if you calibrate your
camera from the start.
My main homemade camera has very long exposures and ever since I first find
out what the optimal times were for different light levels (at first using a
light meter but now by calculated guesswork except in usual or uncertain
light) I do not have to take reciprocity into account as the times stand for
that particular camera with the reciprocity failure 'built in' the exposure
times. It pays to experiment when starting with a camera to find the
optimal exposure times.

As for contrasty paper negatives; what I have done is place a variable
contrast filter behind the pinhole and used multicontrast paper. This gives
pretty good results.

Alexis Rago
Received on Fri Nov 30 14:48:33 2001