Solagraphy is the art of photographically capturing the path of the sun across the sky. As the sun takes a day to cross the sky, the exposure time for a solargraph is at least a day. To really capture the path of the sun as the seasons change (the sun climbing higher as we head from winter to summer, for example) we need exposure times tending towards the length of a season or two – three to six months. You’re not going take these photographs with your DSLR or point and shoot. You need the low sensitivity and long exposure times that come with a pinhole camera.
This is one of the results of my second attempt at six month solargraphy. It is not excellent, but does show the arc of the sun as it crosses the sky. It also show just how few uninterrupted sunny days we have had so far this year.
The photograph isn’t very sharp due to a combination of reasons:
- Movement of the camera – keeping something fixed in position outside in the weather for six months isn’t easy.
- Movement of the photo paper in the camera – humidity and heat and rain all cause the paper to expand and contract and move.
- The size of the pinhole really should be about 0.3mm for optimum sharpness according to optical theory. I used a hole about 0.2mm larger and didn’t thin the material as well as I could first.
I think I shall start having a play with shorter exposure pinhole photography, to develop the skills and materials needed before I try another solargraph.
