AP explains…

Direct Positive paper

Andrew Sanderson explains the benefits of Ilford Direct Positive paper and creating a one-off print

IN THE past couple of years, Harman technology (Ilford) has made available one of the most interesting new darkroom products to reach the marketplace for a long time - a reversal paper. The company has announced it as  primarily suited for use in pinhole cameras where exposure and processing in conventional black & white photo chemistry achieves a unique positive print - without the need for a film negative or inter-negative . Perhaps the most appealing factor of the medium is that it creates a one-off print.

When Harman launched this reversal paper, both RC and FB papers were offered. Last year, though, the firm had a disastrous incident with a supplier that meant all its RC paper had to be dumped

due to uneven coating. Currently, there is only a fibre-based version available, but I believe it was the better of the two papers anyway. The paper is available in many sizes up to 11x14in.

One of the main uses for this paper is pinhole photography. It would seem to be an ideal material for that application, especially when teaching children, because it allows them to see an image directly. My first test was therefore in a pinhole camera.

The paper has very high contrast -something I was unaware of when I first tested it. My pinhole 10x8 camera is constructed to give a super-wide view with a focal length of 90mm (equivalent to a 13.5mm lens on a 35mm camera) and there is quite a  difference in exposure from centre to edge That difference was too extreme in this case.

I tried taking some other pinhole shots using the Walker Titan pinhole 5x4 camera, which has a 35mm-equivalent focal length of 70mm, and got more consistent results The aperture of this camera is f/250. and with Direct Positive paper in the back this gives exposures around 2-3mins in direct sunlight If you wish to try Direct Positive paper in a home-made pinhole camera, make sure you work out what the pinhole aperture f-stop is, otherwise any exposures will be way off the mark. With a commercially made pinhole camera the aperture is laser-drilled so the f-stop is known exactly, but home-made cameras vary wildly in the size of the effective aperture. Combining a known aperture with accurate metering will give consistent results, but even then metering must be done with care because

the high contrast of the paper is unforgiving of over or underexposure.

The ’ISO also needs to be established, although this is relative, the actual speed of the paper can be worked out for a particular meter with a few simple tests. I found mine to be VS stop slower than recommended by Harman, which makes it ISO 2. Check your own results against my speed, but bear in mind that your meter may be calibrated slightly differently to mine.

My next tests were using a 5x4 MPP with a 180mm lens, as I found the control of exposure and narrower angle of view gave more consistent results. As the contrast of this paper is high, even when pre-flashed, the chosen subjects and lighting conditions will have a big impact on the success of an image. I would recommend not shooting into the light and avoiding sunny days unless very graphic black & white shots are desired.

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