Before every summer solstice I aim to make myself a pinhole camera to start a six month solargraph and each year I fail by forgetting. Not this year. I found the perfect tins for this after a couple of presents were finished off at Christmas - Fortnum & Mason Christmas blend coffee and Lemon Curd biscuits. I love them. I hid the tins away until last week when I brought them out to begin the project.
If you're unsure, a solargraph is a image that is made with a pinhole camera. The camera of loaded with photo paper and pointed in the direction that the sun moves across the sky for a long period of time - from days to years. As the days pass, the image is imprinted onto the paper (viewable without chemicals) and maps the sun's movements through the sky getting lower or higher each day. Typically you can do this between the summer and winter solstices to capture the sun's highest point to it's lowest point.
The tins I am using both take a 7x5" piece of photo paper nicely - one portrait and one landscape. I'm using Ilford's Multigrade Art paper by Hahnemuehle which I've had for a while and one of my favourite papers. You'll also need duct tape or electrical tape (duct tape preferably but I didn't have any), a knife, an empty drinks can, a needle, and - depending on where you're loading the paper - a dark bag.
Due to the thickness of the tins, I had to drill a hole 8mm wide into the middle of each of them as trying to force a needle through them wasn't going to work. Don't put too much pressure on the drill either, as it will bend the tin creating a slight lip. I managed to bend it slightly but, with some persuasion with the end of the Stanley knife being used as a hammer, I bent the lip back.
Cut a piece of the empty drinks can big enough to cover the hole you drilled. With a needle, make a hole in the middle of the cut metal. I used a small needle but there was no calculation to get the perfect needle size - any needle will do. I then taped the piece of metal to the tin ensuring to get the pinhole in the approximate middle of the drilled hole.
Normally I would have put lightproof tape on the back of the cut metal with the pinhole in it but I forgot. Doing this would have stopped any direct light leaking in that wasn't coming through the pinhole. Instead I taped up to the pinhole leaving a millimetre or so I didn't obstruct the view.
Put the tin and your photo paper box into a dark bag or move into a darken room to load the paper into the tin. Complete darkness probably isn't necessary for the piece of paper you are using due to the few seconds it will be exposed but you don't want to ruin the rest of your paper.
Finally, screw/push the lids on and make sure you cut a piece of tape to go over the pinhole as a shutter before removing from the bag.
Tape the lids closed and you're ready. To be extra careful, I then attacked the tins with tape and covered every part of them (minus the pinhole/shutter) to block out any unwanted light. The only thing left to do is find your location to install them.
Make sure you attach them to something that won't move and where no one will disturb them. I have put one outside my house since I know I won't and another at my office. I've told people what it is so that it is not confused with anything else or treated as suspicious.
Enjoy and I'll update you in 6 months.