Solargraphy is pinhole photography with an ultra-long exposure: a camera, often a pierced drinks can, exposes a sheet of photo paper for weeks or months, and the sun draws its own paths on it, with no chemicals at all. It takes pinhole photography to a fascinating extreme, that of an exposure no longer counted in seconds. It is a photography of patience, where you entrust a small camera to the sky and come back much later to discover what the light has recorded.
The principle remains that of any pinhole camera: a tiny hole that projects an image inside a camera obscura. What changes radically is the duration, and with it the whole way of working.
An exposure that lasts months rather than seconds
Where a conventional pinhole photograph needs a few seconds to a few minutes, solargraphy exposes the paper continuously for weeks, often from one solstice to the next. Throughout this time, the sun crosses the sky every day and leaves a bright trail on the paper, and the build-up of these passes draws a fan of curves that tell the story of the whole season.
This logic is the exact opposite of a measured exposure. Where a conventional exposure seeks to expose an image correctly in a few seconds or minutes, solargraphy does not look for the right exposure at all: on the contrary, it embraces a massive, continuous overexposure, which is where the whole interest of the image comes from.
The pierced can camera
The classic solargraphy camera is a simple aluminium soft drinks can, with a tiny hole pierced in its side, closed with its lid or with a cap of black tape. Its cylindrical shape works well, because it takes in a wide stretch of sky and curves the image slightly, which accentuates the arc of the sun trails.
The way to pierce it is the same as for making any pinhole camera, a clean hole in a thin sheet of metal, and it is described step by step in the guide to making a pinhole camera. The can is just one container among others, in the same family as the tiny box repurposed for the matchbox pinhole camera, with each format imposing its own image geometry.
Inside, you place a sheet of ordinary black and white photographic paper, curved against the wall, sensitive side facing the pinhole. That is all: there is no film and no setting, and once the can is closed away from the light, it is ready to be put in position.
Installing the camera and forgetting about time
The choice of location decides the image, because the camera will not move again for months and its whole field of view is fixed from the moment it is set up. In the northern hemisphere, it is generally pointed due south to capture the sun's path at its widest, with a fixed landmark in the foreground, a roof, a tree, a horizon line, to anchor the trails.
The mounting must be solid and long-lasting, a strap, a cable tie or screws on a fixed support, because the slightest shift blurs the patiently built-up image. Weatherproofing matters just as much, since the can will face rain and frost, so you carefully seal any openings and all the joins with tape, leaving only the pinhole itself uncovered.
Then comes the most disconcerting part, the wait:
- note the date the exposure started;
- let the camera live through the seasons;
- and come back to collect it after several weeks or several months, without ever having opened it in the meantime.
Retrieving the image with no chemicals at all
This is where solargraphy parts company with everything practised in workshops, because the paper goes through no bath at all. The ultra-long exposure has exposed the paper so heavily that the image has formed directly on it, through the darkening of the sensitive surface, with no developer and no fixer.
So you open the can in dim light, take out the paper and digitise it without delay by scanning it flat. The scan captures the paper image, which comes out in reversed tones, then you invert it on the computer to bring out the positive, and it is this step on screen that often reveals unexpected colours, ochre, purple, copper, specific to each overexposed paper.
Inverting the paper image into a positive is not specific to solargraphy: it applies to any pinhole print on paper, and the two ways of getting a positive are covered in detail in the article on getting a positive from a paper negative.
Worldwide Pinhole Photography Day
Solargraphy is part of a lively community practice, and every spring Worldwide Pinhole Photography Day brings together enthusiasts from all over the world who make and share their images on the same day. Many use the occasion to set up a solargraphy can for the year ahead, which makes it a good calendar marker for starting a long exposure and collecting it the following season.
Accepting a wait of months
Solargraphy requires little equipment and a lot of letting go, because you accept not knowing what you will get for months, and it is precisely this element of waiting that makes it a special experience within pinhole photography. A can, a hole, some paper and patience are enough to etch the entire passage of a season into an image. To get going without building anything, the Sténoflex, a pinhole camera kit with mini-lab, brings together the box, the paper and the developing chemicals.
Éric Marais — Photographer, author of two books on pinhole photography (published by Pearson) and creator of the Sténoflex. He has run introductory workshops in pinhole photography and analogue developing from the very beginning.