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An astronomer’s startling discovery … at the bottom of a cider can

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In September 2020, David Campbell, principal technical officer of astronomy at the University of Hertfordshire in England, found a discarded Kopparberg cider can atop one of the telescopes at the university’s Bayfordbury Observatory. It could have been an innocuous, if oddly placed, piece of pollution. When Campbell discovered a sheet of photographic paper inside the can, he suspected it may be something much more than random detritus. In fact, it was something for the record books.

The can was a roughly fashioned camera that had been taking in light through a small hole opposite the paper. More notably, however, it had been collecting this light for eight years and one month, to produce the longest known photographic exposure ever captured.

An eight-year-long exposure captured through a pinhole in an empty Kopparberg can containing a sheet of photographic paper. Courtesy of Regina Valkenborgh.

An eight-year-long exposure captured through a pinhole in an empty Kopparberg can containing a sheet of photographic paper. Courtesy of Regina Valkenborgh.

“It was a stroke of luck that the picture was left untouched, to be saved by David after all these years,” said photographer Regina Valkenborgh.

It was she who had inserted the photographic paper and placed the can atop the observatory toward the end of her Master of Fine Arts degree at Hertfordshire in 2012. She had actually secured two cans to the observatory roof and returned four years later to retrieve the photos.

“When I took one of them down, the paper had curled up, so there was no image on it,” Valkenborgh told Photonics Media. “And I wrongly assumed the second pinhole was the same.”

Valkenborgh told the observatory technician to toss out the second can the next time he was up on the roof. Fortunately, he forgot.

Another four years later, Campbell would discover the can and its contents that, once developed, depicted 2953 arced trails of the sun, showing its rise and fall over the summers and winters in Hertfordshire.

An enthusiast of analog photography methods, Valkenborgh is particularly interested in pinhole photography, which she describes as “a basic, yet magical image-making method.” She said that this method doesn’t rely on lenses, or batteries, or any of the advanced technology such as the CMOS sensors that have become ubiquitous in smartphones and DSLRs.

To capture an image this way, Valkenborgh places a sheet of black-and-white photographic paper inside an empty beer or cider can — favored over soda cans because those made for alcohol are often taller, thereby allowing a wider image. The task must be performed in a darkroom under safe red light to avoid overexposure. Opposite the paper, she punches a hole for light to enter. The can is then weatherproofed using a thick, light-proof black plastic sheeting, such as pond liner.

In Valkenborgh’s view, the digital medium of photography, though it is able to achieve stunning detail, lacks the “soul” offered by analog.

“Photography’s original photochemistry is hugely important in capturing a ‘true’ moment, as the light of the moment should, in my mind, leave the physical trace on the light-sensitive material, making it a true ‘slice of that time,’” she said.

Of the eight-year exposure taken from the observatory rooftop, Valkenborgh said, “The sun has actually burnt the negative image into the paper.”

This physicality may help to explain the “missing soul” of the digital format. “However,” she said, “whilst having been reluctant to use today’s technology for that reason, I have come to accept that a merger of old and new has greater value than discarding one over the other. These long exposures taken the old-fashioned way would be lost without today’s technology, which preserves it in the form of a digital file.”

Photonics Spectra
Apr 2021
Lighter Side

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