97. Bearing Witness

“Bearing Witness” 10: Done!

Here it is! I’m very pleased with the result. It’s hard to tell on a video because the candles are brighter than the dark painting so they over-expose the camera, but I think I’ve done a good job on simulating a flame. As time goes on I’ll experiment with assorted ideas for improving the effect.

The flash is good, but not quite what I hoped. I think the problem is that the flash points at the painting, which uses predominantly dark colours, so the amount of light reflected is limited. I suppose I would have liked to point the flash directly a the viewer. With around 3000 Lux that would certainly catch their attention.  They would also walk around with dots in front of their eyes for the rest of the day, which wouldn’t be such a good idea.

In fact, user testing (i.e. unsuspecting visitors) showed that people just don’t like unexpected flashes (or possibly flashes of any sort). So I changed it to slowly fade in and then out over a period of about 10 seconds.

psu-12vThere is a small problem with this. I’m using PWM (“Analogue out”) on the Arduino, which switches the output at either 490 or 980 Hz (I’m not sure which – it depends on which pin the Flash is connected to). This means that the poor power supply is having to produce 3 Amps, then almost nothing, then 3 Amps, then almost nothing, then… The upshot is that the PSU produces an audible whistle during the “flash”. I tried to reduce this by adding a 1000 microFarad capacitor to the electronics (across the power socket), but this didn’t seem to help. I considered changing the software to use a higher PWM frequency (e.g. 64 kHz), but after discussing it with the artist we decided it wasn’t a big enough problem to warrant making changes now that it had been well tested.

Thanks again to George Sfougaras for the creating the original artwork and for encouraging me to be creative in lighting it.

The work was shown at the exhibition “The Eye” in central Leicester (12th January 2017 – 8th February 2017).

We are happy that the work has found a permanent home. It was installed in a local Synagogue in time for the 2017 Holocaust remembrance evening. The contemplative reflection encouraged by the flickering candles, and the infrequent short sequence of bright flashes (to which it has been reverted), work well in this context.




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