> The basic problem we have to solve negative is the following: how do we > make a contact print of a 12.5 x 8.5 feet paper negative with > substantial over- exposure in the center and substantial vignetting at > the edges. This has raised much more complicated questions than just > preparing the basic room set-up for the exposure and calculating pinhole > size, f/stop and exposure time to create the negative. I would suggest (and I think this was suggested before) to use a small "peanut" sized high intensity light bulb (actually any small light source that sends light out in all directions would do) and place it close to the paper maybe in the same position that the pinhole was at when the negative was made. Then, according to the inverse squared law the illumination should fall off radically towards the edges of the print. Placement of the "point source" will control the difference in light level at center vs. edges. Now, what happens in the middle gounds .. that is another story! as for the yellow coloring of the water ... hmmmm ... it should not happen. adios, andy
