Toronto. … as my mother used to say when she felt that I was dragging my heels. But sometimes taking your time is beneficial. Photographic media are sensitive to the volume of visible light hitting the sensitive surface. Traditionally two means were offered to control this volume: a shutter to determine its duration, and an aperture to set the amount of light hitting the media per unit of time.
The very simplest cameras were pinhole cameras – a fine pin hole for a lens and a piece of sensitive media, all in a light tight container. Photographer Regina Valkenborgh recorded the above photo in 2012. She calls it “Days in the Sun”. Regina used a beer can pinhole camera exposing directly on photographic paper for SIX MONTHS!
NASA accompanies the photo in its “Astronomy Picture of the Day” column with, “From solstice to solstice, this six month long exposure compresses time from the 21st of June till the 21st of December, 2011, into a single point of view. Dubbed a solargraph, the unconventional picture was recorded with a pinhole camera made from a drink can lined with a piece of photographic paper.
“Fixed to a single spot for the entire exposure, the simple camera continuously records the Sun’s path each day as a glowing trail burned into the photosensitive paper. In this case, the spot was chosen to look out over the domes and radio telescope of the University of Hertfordshire’s Bayfordbury Observatory. Dark gaps in the daily arcs are caused by cloud cover, whereas continuous bright tracks record glorious spells of sunny weather.
“Of course, in June, the Sun trails begin higher at the northern hemisphere’s summer solstice. The trails sink lower in the sky as December’s winter solstice approaches. Last year’s autumn was one of the balmiest on record in the UK, as the many bright arcs in the lower part of this picture testify.”