Long exposure times are interesting. While fast films and sensors allow short exposures to freeze movement, a long exposure can show life through that movement. There's a wonderful Atget photograph (aren't they all?) of a white horse in front of a church: Its two heads and five legs are a photographic 'defect' but that little bit of life shown by a restless animal on that sunny day 120 years ago has been preserved:
Very long exposures usually obliterate animal or human life. The famous daguerreotype of the Boulevard du Temple in 1838 shows a man having his shoes shined. He and the boot black boy stayed still long enough to be recorded while everyone else passed through the minutes-long exposure like ghosts.
Exposure duration and subject have to match to make a picture work. Usually the subject is chosen (waterfalls, lights of traffic, waved torches or other photography guide clichés) and then an exposure time devised to show the movement, but what if your process is inherently slow, like say a pinhole camera?
Using the 'lumen' effect of photo paper, just letting it darken with exposure without any development makes possibly the least sensitive photo material of all. A pinhole aperture means the time needed to record an image is measured in weeks or months. Nothing moves slowly enough to be recorded over such time - except the sun..
I should note that I'm not claiming to have invented this technique. Many people including the excellent Justin Quinnell and Angela Shaw have made pictures like this. I've never got around to making one until this summer.
I made a simple pinhole camera from a coffee can. Cylindrical cameras are good as they cover a wide angle of view and the camera needs to be well sealed from the elements as well as light. I made a small wooden bracket to support it at the right angle and braced it as solidly as I could. It mustn't budge even a fraction of a millimetre for months.
Installed on May 10th 2022, I then left the camera untouched until September 13th. That's an 18 week exposure, or nearly eleven million (10,886,400) seconds. There's no special significance to the time period but the summer months are most effective, comparatively little exposure happening in the winter.
I used Ilford Multigrade IV resin coated paper secured inside with tape.
As it's a lumen image, it remains light-sensitive. Just looking at it for too long under normal indoor lighting will affect the print. Scanning fogs it almost instantly! The safest way is to rephotograph it under low lighting with a DSLR.
At first glance it's a bit underwhelming. There's an image but it's pale and flat. However, inverting it in Photoshop and boosting the contrast a bit makes all the difference:
The path of the sun changes a little every day, getting higher and higher in the sky towards midsummer. The dotted lines show when it was intermittently cloudy. The colour is interesting: The natural brown and magenta tones of the neg reverse to blues, greens and yellows which just happen to correspond to natural(ish) landscape colours of sky, trees etc. It's not as sharp as I'd hoped- I think the camera mount may have moved during the very hottest days. - I'll have another try next year...