The shoebox pincam has been more difficult to master than I had anticipated. In my previous blog post I recorded the design and construction, followed by a test exposure which I estimated to be a little over exposed. This was followed by an exposure that I expected to be good, taken on an outing to a tidal island and for which the pincam had been planned. That second exposure was uselessly overexposed and after some consideration I put the reason down to my error in metering the scene. Yet I’ve been unable to settle comfortably with that conclusion and so I set out this last weekend to have another go with the camera.
To recap: the camera has a constant radius curved image plane to be loaded with four (originally five) 5×4 sheets of direct positive paper taped together to make a 5×16 (originally 5×20) image. After the first two exposures I realised that the angle of view did not extend to a full 180º, but only to about 145º. By adjusting the support for the paper to accommodate only four sheets not only did I save a sheet but I avoided an ugly vignette at either end of the image.
For my testing on Saturday, I returned to the same riverside location that I had used for the original test. Conditions were much as they had been before and I made a similar exposure. When the image was developed I was surprised to find that each of the sheets making up the image were differently exposed/fogged. On the one hand I was puzzled by this while on the other I was relieved that the problem was clearly not one of my metering of the scene as each sheet had received the same exposure!
Assuming a light leak, I made some alterations to the light baffling on the lid of the shoebox, reloaded and returned again. This time all four of the sheets were clearly fogged, but not to the same degree. On one of the sheets there was even a clear difference in the pattern of fogging across it. It was enough to make me suspect either my safelight or (less likely) that the box of paper was bad.
Sunday was a dull, wet day but I have a pincam made from foamcore that is completely covered in gaffer tape rendering it effectively rainproof. I decided to make two exposures with it, one on paper loaded in the total darkness of a changing bag and the other on paper handled as it would have been for the shoebox pincam under the regular safelight in my darkroom. The results convinced me without any doubt that the paper was being fogged by proximity to and time under the safelight.
Towards the end of the afternoon the rain eased and the sky began to clear. By that time I had devised a support-cum-guide to speed up the process of lining up and taping together the individual sheets of paper. I had also relocated the safelight so that I would be working in its shadow and further away from it. With about two hours of daylight left and I decided to head out again for the riverbank. I had no expectation of there being enough light to make a full exposure but actually a couple of stops underexposure would better show up any fogging.
First test image
My darkroom is a temporary setup in a shower room. The walls are matte white and the work surface glossy white. For a safelight when taping together and loading these sheets I had used an old bicycle rear light which gives off a weak red glow, set on the work surface.
Had it not been for what I now recognise as fogging in the right-most sheet, I would have said this image is just overexposed a little with perhaps a light leak from somewhere. However with hindsight I realise that the rightmost sheet was exposed longest to the safelight and closest to it. The light edge to the left-most sheet should also have alerted me to fogging as the cause.
Second image (not originally intended as a test!)
Again, I should have realised this was fogged rather than overexposed. The vignetting at either end is clear and with direct positive paper any unexposed portion should be black.
When loading these sheets I had set up my regular deep red safelight, positioned on a hook about 1.2 metres above the work surface. Taping each of the five sheets together takes some time and I was doing so with the paper face down on the glossy white surface. Under the red glow it was difficult to see where the edges butted together to place the tape. I took all five sheets from the box at the same time so all were exposed to the safelight for the same length of time, probably three or four minutes.
Third test image
These sheets were loaded under the regular darkroom safelight as before but this time removed from the box one at a time, as needed, and kept face down on the work surface as much as possible. I had to reposition the tape on the third sheet and it probably had more direct exposure to the safelight as a result. The light edges all around each sheet suggest that fogging was occuring from light reflected off the work surface.
Fourth test image
This was loaded much the same as for the previous image. At this stage I was looking to the camera construction as the source of the fogging and had reworked some of the light-baffling and sealing on the camera. I was becoming more proficient at taping the sheets together which I think has led to more consistency in my handling of the paper and the subsequent degree of fogging.
Fogging test and resolution
This is the test pincam in the rain (left) and the two images which clearly show the difference between the paper being loaded entirely in darkness (centre) and having been handled under and exposed to for a couple of minutes, the darkroom safelight (right).
To resolve the fogging problem I moved the safelight to a different hook so that it would be further away from the work surface and in such a position that I would be working with the paper in my shadow.
I also made from black foamcore and mountboard, a support and guide that would both prevent surface reflections affecting the emulsion side of the paper and assist lining up and taping of the sheets. A second piece of mountboard was used to cover each sheet as the taping progressed, thus minimising and equalising the exposure each sheet received from the safelight.
Although this is almost completely black due to underexposure by two to three stops, the black is actually quite a joy to see. Had the paper been fogged while being loaded, that black would at best have been a lighter shade of grey. There is no suggestion of fogging around the edges of each sheet and consistency of exposure across the entire image is clear.
Conclusion … and a final thought
It has taken an entire box of Direct Positive Paper to reach but I reckon I can safely and comfortably conclude that the problem has been fogging due to overexposure to the safelight. I can also conclude that a resolution has been found.
One final thought: I’ve been using Harman Direct Positive Paper for almost four years. Why have I not noticed this before? The answer is that without realising it, there have been times that I have! Mostly I load single sheets directly from packaging to camera or film holder, often in a changing bag, and there has been no problem. However there have been times when paper has to be cut to size. Often, cutting a single sheet does not expose it sufficiently to be fogged but if I’ve been cutting a batch I’ll have had a growing pile of paper sitting in the light. Those are the cut sheets that didn’t produce the same contrasty ‘punch’ that I expect and love about this paper. Lesson learned!
All that remains will be for me to make a few good exposures in the weeks ahead. And they will have to be good as I have only one box of paper left. There’s no room for error either as I’ve discovered that it is currently unavailable from Harman and out of stock wherever I’ve looked!