[tutorial] Solargraphy

Recently the YouTube algorithm flushed a video about Solargraphy into my feed. It’s an easy to copy photographical method to capture the course of the sun during the year (or shorter times) with minimal material and work. The only things you need to get started are a pinhole camera and photographic paper (enlargement paper).

Although you can buy ready-made pinhole cameras or even print your own, I followed some tutorials (here, and here), to build my own ones.

Build your pinhole camera

A pinhole camera is basically just a light-proof container with a tiny hole at one side. To build mine, I tried multiple ideas that I saw online.

First, I used beverage cans, where I stuck two together as described in the Instructables page that I linked above. Those cans bent and folded in my backpack though, so I couldn’t use them, after transporting them. So I will skip these in the following text, although you will see them in some pictures.

I also had a tin can with thicker walls, that used to contain tea, so I used that one instead. Also, at work I had many empty 35 mm film containers, that I saved from the trash. I also used those to build some pinhole cameras.

I drilled a 5 mm hole in the film containers, about in the middle (height wise) and filed away the fuzzy borders of it. Then I cut out a rectangular piece of a beverage can, also filed it thinner and poked a hole in it with an awl. This makes sure, that the pinhole is as small as possible, and the wall is as thin as possible. I then stuck the piece of aluminum over the hole in the film container, making sure it’s centered. I used gaffer tape to keep everything in place.

The tea container is basically just a scaled-up version of the film containers and was fabricated the same way.

Put in the photographic paper

Later I cut a piece of paper to fit in the container, so I could figure out the maximum size of photographic paper to fit in the several containers. Also, I painted the aluminum pieces black with a permanent marker, to reduce the reflection.

Luckily at work I have access to a dark room, where I could cut and fill the the paper.

After putting the paper into the container, I covered the pinholes with more black gaffer tape and for the tea container I also glued the lid to the box, with tape, so no light could enter.

Expose the film

Finally, everything was ready. I stuck the cameras on two different spots, facing approximately to the south, to south-east. Then I removed the tape in front of the pinhole and waited patiently for half a year to pass.

After that time, I closed the pinhole and put the paper on a scanner. It is not necessary to develop or fix the paper, it even should be avoided. After such a long exposure time the light is „burned“ into the paper, and you get a clear negative image of the course of the sun.

Obtain the image

When removing the photographic paper from the two film containers and one tea box, I chose a dark(-ish) place, since the paper is still photosensitive. The paper looked like this:

I scanned in the images at 600 x 600 dpi and inverted the colors in Gimp. I also adjusted the values and white balance a bit. Here are the first results:

What’s next?

I am happy that the method worked on the first try, yet I see some space for improval. First of all, the first two images show some weird freckles. I think that might be from dust, as those two cameras were placed on a main road and next to planting pots. I will inverstigate that.

Secondly, on the last picture you can see that the image is quite blurry. I think that might have two causes: The pinhole wasn’t small enough, and the camera was a bit shaky. I will address both these things in the next round of exposures.

In the pictures above, you can see, that the tip of my awl was broken and it didn’t really produce super tiny holes. So, I build a new awl from a piece of wood and a sewing needle to punch tinier holes in the beverage can aluminum. On the last picture you can see how gigantic the old hole appears to be, compared to the new one.

To make the camera less shaky, I constructed a frame in Fusion 360, that I will print. At the bottom it will have holes to attach 6 x 2 mm neodymium magnets, that I have still laying around and spacer pates to adjust the angle. The film container can be fixed to the frame with tape, at the backside.

Finally, I want to test other kinds of film. So far, I only found tutorials, where photographic paper was used. But I found a flickr post, stating that regular 35 mm film will work as well. I have large amounts of expired iso 400 and ISO 25 b/w film and also some very old, expired x-ray film.

Below you can see the paper I used and the 35 mm film. Unfortunately, I forgot to take a picture of the x-ray film.

I plan to place cameras with RC-Paper, X-Ray film and regular film next to each other, to compare the results. I will update you in half a year, I guess 😉

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