‘Longest known exposure’ recovered from makeshift camera forgotten on UK telescope

At an effective 'shutter speed' of eight years, the ethereal shot—taken using a pinhole camera made from a drinks can and a sheet of photographic paper—may be the most extreme example of its type.

At a glance it looks like a semi-pleasing printing error. Or a photo taken by mistake, filled with claustrophobic depth of field, shadows and murk—like so many accidental 'closeups' of the inside of a camera bag. But to those who know what they are seeing, this image bears a distinctive visual fingerprint shared only by a relative handful of others. And its makers believe this could be the most remarkable example of all.

The lines climbing the image are a recording of the sun’s path across the sky, rising and falling with the seasons. Eight full cycles of them, in fact—exposed through a pinhole aperture onto a piece of photographic paper inside a cider can, which almost a decade ago was pointed at the horizon and attached to a dome at University of Hertfordshire’s Bayfordbury Observatory. Then forgotten about.

The camera was rediscovered in September 2020 by a technician, and the image inside successfully retrieved. Now, it's believed that at eight years and one month, it could be the longest photographic exposure ever made.

What did this camera see?

Though indistinct, the image is actually of a landscape dominated by the sky. The dome of the observatory’s oldest telescope can be seen bottom left, whilst a steely gantry can be identified to the lower right. 

The photographer was Regina Valkenborgh, who in August 2012, was completing an MA in Fine Art and was tinkering around with the home-made pinhole cameras, attaching them to the domes of the observatory's instruments. Now a photography technician at Barnet and Southgate College, London, she says at the time she wanted to “explore the time concept in photography which makes the invisible, visible.”

“My reason for using pinhole photography was because of its experimental nature,” Valkenborgh told National Geographic (U.K.) in an email. In her image, “long exposures show the sun’s trails in the sky as the earth orbits the sun. The axial tilt of the Earth becomes clearly visible on the pinhole image with the summer solstice being shown as the higher arches at the top of the image, and the winter solstice as the lower arches just above the horizon.”

“However, what’s more unique about this is that although the invisible has been captured, it has also erased the visible,” she adds. Over the years, you’re able to see the sun trails, however you’re unable to see the thousands of people who would have visited or worked at the observatory.”

The camera was constructed from duct tape, a 500ml Kopparberg cider can— Valkenborgh says she prefers beer or cider cans because “they are taller than soft drink cans, so [produce a] bigger image”—lined with Ilford Multigrade photographic paper. Her longest previous exposure using such a device had been a year, which she described as “visibly different” to another she had made over six months.

Extreme exposure

Long exposures are common techniques, and often employed as a photographic rite of passage by experimental amateur photographers. The images produced often elevate mere snappers into a more artistic realm, as they demonstrate the ability to control shutter speeds and record movement to creative effect—essentially to ‘see,’ then capture, what isn’t immediately visible.

The results can be satisfyingly dramatic, ranging from using an exposure of a second or two to dreamily blur moving water, to several seconds to record the car traffic tracing a route in headlight streaks—and anything from a minute to several hours to record the earth’s movement against the stars in sweeping astral arcs. 

Longer exposures than this are rarer, and harder. They risk over-exposure or over-abstraction, and exhaust camera batteries, the patience of the photographer, or both.

Valkenborgh's image evidently sidestepped such problems by being needless of all: as a pinhole camera made from a can, no electronics were needed to hold open a shutter. And being forgotten about, patience wasn't a factor either. Combined with a photography technique as old as the art itself, the resulting image is both technically impressive and possessive of an artistic charm of its own. The sun trails—a possible 2,953 of them, according to the University’s press release—in the most literal sense stamp a photographic timecode on the image. Eight years, in one shot.

“I see the image as a calendar and a ‘weather map’,” says Valkenborgh. “As well as showing the seasons, the bright bands mean it was a sunny day and dark bands were cloudy days. Some days you can see a circle instead of a line and this is where the sun broke through the cloud cover.”

“This is a stunning—and extreme—example of its type,” Dr Michael Pritchard, Director, Education and Public Affairs at the Royal Photographic Society, told National Geographic (U.K.). “Regina has been fortunate that no-one disturbed her camera for so long, and she produced a wonderful recording of the way the sun moves with the seasons over time.” 

Through the pinhole 

Utilising the so-called 'camera obscura' effect—where light passes through a tiny hole and projects an inverted image on a surface—pinhole photography is believed to be the first articulation of modern photographic principles.

“The idea of a room camera obscura with a smaller opening to create an upside image of the outside world goes back to China in the fifth century,” said Pritchard. “By the fifteenth century artists were using portable camera obscura with lenses as an aid to drawing. With chemical experimentation of the early nineteenth century it was the ideal tool for Wedgwood, Talbot and others to try and secure a permanent image using chemistry and optics.”

(Video: How to create your own room-sized camera obscura.)

As photography became more mainstream, such cameras stayed in vogue as a tool of artistic expression—a trend that continues, according to Pritchard. “Pinhole photography has remained of interest—to artists wanting to add something different to their work to school children being shown how light behaves, and how traditional chemical photography works.”  

An inexact science

The downside of long exposures using traditional film methods is a reliance on the chemistry of the photographic medium, in this case the paper, retaining its sensitivity to changes in the light before it hits a wall—rather like a saturated cotton wool pad that can no longer absorb water. This is known as reciprocity failure, and can result in color casts, patches of lost detail, or simply no further changes in the image. 

While the eight year exposure stands regardless, Valkenborgh accepts that at some point the paper probably stopped recording detail—and that “it may not have 8 years’ worth of sun trails overlaying each other.”

The man who found the camera attached to the dome, however, believes the camera may have captured a surprising amount of the exposure period. “The image was changing until at least 2018, as the gantry was not built until the end of 2017 and it is quite clearly defined,” says David Campbell, Principal Technical Officer at the Bayfordbury Observatory.

The camera remaining necessarily static appears to have been pure luck—and actually contradicted Valkenborgh's intentions for the image. She says she placed the camera on the dome to capture the “movement in the sun’s trails” when the device it was mounted on was “spun around to look at different parts of the sky.” As it happened, it didn't move much at all.

“The dome it was attached to was never really utilised in that way,” says Campbell. “It was an atmospheric instrument in 2012, but In 2013, a telescope was put in there instead. This meant that the dome would really only move during the night and return to almost exactly the same position by the time the sun rose.”

Campbell concedes that there would be the “odd time the dome moved during the day—maintenance, faults etc.” These minor interruptions are recorded in the image as minor changes and breaks in the sun's streaks, such as in the bottom right-hand corner. But one aspect is undoubtedly dominant, with Campbell adding that “99% of the time the camera was in more-or-less the same position over 8 years.”   

Record time

Despite the image's accidentally long duration—or because of it—eight years and one month is a formidable record to break. Other extremely long exposures have been successfully and intentionally shot, notably by German photographer Michael Wesely, whose work with large format cameras has included successful exposures of up to 34 months

And more are, very slowly, in the works—including a plan by American experimental philosopher Jonathon Keats, whose 'Millennium Camera', installed above the skyline of Tempe, Arizona, began recording an image in 2015 that its maker has requested to remain undisturbed until 3015—an exposure of 1,000 years. In any case, success is by no means guaranteed.

“The basic idea is not difficult, but it relies on the camera being undisturbed for a period of time,“ said Michael Pritchard. "It is susceptible to curious passers-by or vandalism, and being weather and animal proof. If you’re making the camera from scratch with an old can then ensuring the pinhole is small enough, and making the camera weatherproof are the two main factors to ensure success. The chemistry for developing the photographic paper is straightforward to use.”

Alternatively, some manufacturers have designed their own ready-made devices for such photography, or 'solography'. 

Whether or not Regina Valkenborgh now holds the record for the longest-exposed image, it's hard to be definite. There may be longer exposures elsewhere, intentional or otherwise, but if there are, they remain obscure.  

Michael Pritchard of the RPS doesn't know of any. “It’s very likely that this is the longest exposure by such a device on record,” he said, noting of the image's aesthetic value: “Regina should be proud of achieving such a successful photograph. It really is stunning.”

Of her image, Valkenborgh is delighted the camera was saved. “The fact that a simple aluminium can lined with photographic paper can create something of scientific value in our technology driven world amazes me,” she said.

“Photography is often used to centralise and immortalise our existence, and this image does the exact opposite. I see this as a poignant reminder of human life being part of something much bigger.”    

This article was adapted from the National Geographic U.K website.

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