Light Painting with a Harmonograph - Part 4
22 Jan 2022 9:46AM
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Part 4 – Exploring a more ‘Ethereal’ Space
Once or twice, I got lucky with ‘octave’ tuning and made some striking images. The one below I called ‘Harmony’ – I liked the little rings towards the centre; they draw the eye and fix the image.
Harmony
I wanted to explore more this tuning space, as it seemed to have the potential for different, more ethereal images without obvious symmetry. The difficulty is that the upper platform is not a ‘simple’ pendulum (ie it is not like a weight on a string). It is a ‘compound’ pendulum and the weight at the top has a significant effect on its swing period: for a simple pendulum the period decreases as the square root of its length; for a compound pendulum it may well increase when you are trying to decrease it! Imagine a rigid pendulum with equal weights at the top and bottom – it won’t swing at all (ie infinite period)!
In the configuration I am using, it is also different for the two swing directions as well, so we get stronger precession as I try and shorten the period. Any adjustment – such as altering the length, lens zoom, or even focus – affects the precession, so adjustments take a lot of time and don’t always work.
The way I took around this was to use an upper pendulum in the shape of a Y, shown below. A Physicist might call this an ‘anisotropically suspended pendulum’. They come up with such wonderful phrases! – my favourite (and one of the most beautiful) is probably the ‘Hertzsprung-Russell Diagram’.
wiki . Here a Y shape is a good description!
Y pendulum
This was a configuration used by Blackburn in his original idea, as it has two periods and will form a good pattern on its own. It was also suggested by another friend, and fellow laser designer, Jens. I happened to have a drum of very thin multicore steel wire (4 cores, 0.1mm thick, copper plated high tensile steel, lacquered for insulation, cotton wrapped). I bought this about 30 years ago for a few pounds, thinking it would come in useful sometime. It was ideal for this – very strong and I could run the LED current down the wires – even multicolour as I had eight connections. It also wasn’t going to snap and drop the weight down onto the camera (although I was very cautious to start with!).
I also slowed down the lower platform by suspending it with extension rods from the upper gimbal frame, so I could then easily achieve a 2:1 ratio, with very slow decay. I made the wire pendulum micro-adjustable by winding it on a small drum and started to explore!
This image proved very popular at the recent Art show (I wrote a short blog on this experience) – I have now made several large prints of it. Fabio made a very etherial 'sonification' of this image
here. The three elements are similar but different; all I have altered is the starting swing strengths and timing (there are still a lot of variables!). The first form seems to me like a speech bubble, but with a harmonious note emanating from a point. The next is like a stylised figure, in a long dress, dancing through the air and the final form is something leaping into the air, taking flight or maybe a manta ray, gliding though the ocean. OK, it is abstract and you will undoubtedly see something different, but I think the forms go well together, and show progression. The near octave tuning makes this work particularly well I think, as the underlying form is simple and doesn’t have clear symmetry.
The lead image for this part of the blog is entitled ‘Metamorphosis’ this seems to show progression from an egg like form, which twists then grows and finally breaks out. It maybe works better when viewed vertically (the final form is more bird like). I captured around 30 images to build this, trying to give the right level of progression, with no jogs or disharmony, so quite a bit of work!
This image appears almost solid, which is result of the very slow decay on both platforms. Most of the motion is from the lower platform, painstakingly adjusted to virtually eliminate precession, with only a slight motion on the upper. It is always tempting to give everything a good swing, but it doesn’t necessarily give the best images! Seeing what comes out, even when I know the approximate form, is still really exciting with this machine! I love this image; it is, to me, ethereal, sensuous and enigmatic.
The words of this beautiful song go round in my head when I’m working with these harmonographs. I know I used this as a banner for an earlier part, but I’d like to talk about it.
Windmills of Your Mind
Noel Harrison
Round like a circle in a spiral, like a wheel within a wheel
Never ending or beginning on an ever spinning reel
Like a snowball down a mountain, or a carnival balloon
Like a carousel that's turning running rings around the moon
Like a clock whose hands are sweeping past the minutes of its face
And the world is like an apple whirling silently in space
Like the circles that you find in the windmills of your mind!
Like a tunnel that you follow to a tunnel of its own
Down a hollow to a cavern where the sun has never shone
Like a door that keeps revolving in a half forgotten dream
Or the ripples from a pebble someone tosses in a stream
Like a clock whose hands are sweeping past the minutes of its face
And the world is like an apple whirling silently in space
Like the circles that you find in the windmills of your mind!
See what I mean!? …
like a tunnel that you follow to a tunnel of its own… For this image, I have used the near octave tuning, with a bit of additional complexity from the sideways motion of the Y pendulum and colour from two adjacent LEDs. The pin holes don’t exactly line up, so this gives some angular dependence on brightness (just as for the blue/yellow toning for the single LED images), giving additional interest and complexity. The colours aren’t switched, but change and blend naturally as the platform rotates. The three images have progressively longer exposure times. Magic, eh!
In the next and probably final part, I’ll talk about 3D imaging with the machine and some potential future work. I hope you have enjoyed this so far!
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