Lightpainting with a Harmonograph Andrew Carter
19 Jan 2022 5:07PM
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Introduction
I’ve been posting images from my harmonograph project ‘Harmony of Light’ for the last year or so on EPZ and have been evolving the machine and the type of images I can produce with it. I thought it was about time to write the project up as a blog, so you can see what I have done and how these results have been achieved. I’m planning the blog will be in 5 sections so each individual part will be quite short and hopefully readable; it will also give me time to add or modify and respond to any questions or suggestions! If, however, you are impatient and want to see more images, you can view my gallery on SmugMug or look back through my EPZ images. I hope you enjoy this – comments and feedback appreciated!
I am a lifetime enthusiast photographer, but my career has been in Optoelectronics and Engineering, designing and building the devices that power today’s optical transmission for the Internet – so I have a good grounding in Optics and Engineering! When the pandemic hit, members of our local camera club were looking for activities to try, share and learn from, but at a distance. I chose to build a Harmonograph, which I thought would enable a good variety of images to be produced. I have really surprised and delighted myself! I am discovering new options and patterns almost daily; it is enabling me to explore a range of photographic images which I think are unique and unbounded! It’s a project that has brought together many of my interests – photography, engineering, physics, woodwork, electronics, computing, art and music…. I cant think of anything else that could have done this!
A Harmonograph is built around the pendulum. Victorians were amazed and enthralled by the pendulum. They were used to prove the rotation of the Earth (Foucault) and to measure the minute differences in the force of gravity at sea level, the tops of mountains and the poles. The Harmonograph (there is plenty of material on the web) became a ‘gentleman’s toy’ and could produce quite intricate and beautiful patterns, almost by magic. It was invented in 1844 by Scottish mathematician Hugh Blackburn. A traditional harmonogram is the record of motion of two or three pendula, using either a pen and paper or a needle and smoked glass. Hugh Blackburn’s original machine actually used a bag of sand, which flowed out through a small hole to produce a pattern on the ground. For more details, look on the web. There are many configurations and designs available, as well as plenty of programmes and apps that simulate harmonographs. They produce complex and interesting patterns but seem to me a bit synthetic and flat. I wanted to try and make a harmonograph that recorded the image photographically, so that the velocity of the light source would be correctly rendered through intensity in the image, giving a 3D feel that is absent from pen/ink renderings and computer generated harmonograms.
Example Harmonographs from the Web
Simulations by my genius friend Adrian Janssen
My prototype was built with a stepladder, wood (chipboard!), double sided tape, wire and string. I started by thinking and playing rather than looking and reading about past work; this can lead to more invention, rather than similarity. I finally ended up with a unique machine that is completely different to anything you might see on the web! and with a far more extensive capability (I think!).
My early prototype, based on a step ladder!
This operated surprisingly well and it taught me a great deal about what worked and what didn’t. It produced interesting results, but was limited in its settings, and the motion decayed quite rapidly, so I didn’t really get the 3D ‘feel’ of the images I was after. Its main limitation was in the ability to tune it – ie alter the swing periods of the two platforms. I also couldn’t adjust or control ‘precession’. If you look at other harmonograms on the web they virtually all show evidence of ‘precession’. The motion of a platform goes from elliptical to linear and back to elliptical. It is due to the platform having a slightly different swing period in the two directions; the motions couple together, giving this effect. Mode Coupling (as Physicists would call it) is very common in science and nature – it can even apply to a combined population of rabbits and foxes in a field or light generation in a laser (Physicists love this sort of stuff)!
'Into the Egg' - probably one of the best images from the stepladder!
A little precession is OK, but too much is distracting and makes the images ‘samey’, so it needs control. The image from my prototype ‘Into the Egg’ is dominated by precession of the upper platform.
Another quick piece of learning was that the LEDs are quite large – so to make the lines ‘pixel sharp’ you need a pin hole or other small aperture on the LED. I used aluminium tape and a fine needle to do this. The ‘Into the Egg’ image also shows quite attractive colour toning – I liked this, but wanted to know why it occurred and if I could control it! White LEDs start with a deep blue or near Ultra Violet emitting chip which then is converted to white by a surrounding phosphor. The colour shading comes from the pin hole allowing different proportions of the white and blue light through at different angles. Many of my subsequent images use this native colour toning.
I also found out I needed a stack of ND filters on the camera, and to keep the room dark! Having the stepladder in the house also wasn’t popular or elegant… so it was over to the workshop for the ‘block 2’ variant, which I will talk about in the next part.
