A Solargraph is a looooong exposure image, taken using a pinhole camera that’s been left somewhere for upwards of a month at least. Using photographic paper instead of film to effectively burn the path of the sun into the paper, it traces the arc of the light as it passes through the sky. With an exposure time of 6 months, you can see how the sun’s path changes over the months, hopefully capturing some scenery in the background too.
I’ve been lucky enough to live near Pensford Viaduct in Somerset for the past couple of years, and thought it’d make the ideal backdrop (well, foreground, technically) for a solargraph.
This is my 6-month exposure, set up in October 2017, and taken down in April 2018. You can see the viaduct in the background (smaller than I imagined!) and our garden fence in the foreground. There has been some darkening and bubbling (water damage maybe?) in the middle of the image, but other than that I think it’s fared very well!
To make my solargraph, I used an empty Illy coffee tin (one of the small 125g ones), and punched a tiny hole in one side, about halfway up, with a nail and some sandpaper. In a dark bag, I slipped in a small sheet of photographic paper (around 10cm x 14cm, emulsion side in of course) and taped the lid on with black gaffer tape. I was careful to make sure the edges of the paper didn’t overlap the pinhole. After the applicatin for some more tape, I affixed my camera to the drainpipe outside the kitchen window, and left it.
After taking it down, the only thing to do was scan the photo, using a normal flatbed scanner. No fixing is required, as the image is effectively burnt into the paper. It comes out looking a bit brown and pale, but once you invert it, import into Lightroom and play about with the contrast quite a lot, you get a useable image!
If you want to have a go at your own solargraph, I’ve heard great things about the Solarcan (I’ve even backed it on Kickstarter, so I’ll have to think up another cool place to leave the next one).