A little belated here, but in April it was my pleasure to attend a workshop given by the Joshua Light Show. These are the fine folks who produced the pioneering psychedelic light shows literally behind some of the greatest music acts of the Sixties.

They started by presenting gentle diffusion effects created on an overhead projector by putting pigments in a clear glass dish with water. As the projector bulb heats the fluid, convection currents fan the pigments into complicated tendrils and turbulence.

The next step up was adding some clear and pigmented oil: because this does not mix with the water-based pigments, it forms delightful colored space bubbles and amoebas. Important professional tip: the dishes they used were the cover glasses from clocks, which are gently concave with reasonably flat bottoms. Nesting the dishes with different fluids between them yields different lovely effects: tilting them can give a gradient colors, and raising/lowering nested dishes in time with the music yields the pulsating-amoeba effect that can be so synthaesthetically pleasing.

Instead of an overhead projector, one member of the troupe used a digital SLR with a macro lens focused on a petri dish of fluids, underlit by an iPad with a video synthesis program. He would put various fluids in the dish which would refract the video in interesting ways. One neat trick was to put shiny metallic dragées (sugar cake decorations) in the dish: as the sugar dissolved the metallic coating did interesting things with the light.

Later they talked about Lumia, which is an art form started by Thomas Wilfred early last century. In its most basic form, collimated light is reflected from a deformable mirror, which generates beautiful optical caustics like the light that refracts through a wine glass.

In the old days, they reflected slide projector images from flexible mirrors, which they flexed by hand in time to the music. They showed some vintage projectors with hand-painted geometric slides. A modern twist is to use the light from a video projector: videos of a burning candle and a high-contrast dancer yielded some lovely effects. One more pro tip: a good type of mirror for that effect is a "ferrotype plate" which is stiff but flexible, highly polished sheet metal used as the substrate for ferrotype photographs. Looks like you can buy ferrotype plates on-line

And they had racks of other mirrors as well, including a chromed salad bowl, mirror tile on a flexible foam backing, and various things they had made out of mylar. Nothing you can't do yourself!

So that was the workshop, very interesting and informative to see the lovely effects generated by very simple processes. If I had one regret, it would be that even after some epic shows with The Who, Hendrix, Jefferson Airplane, Clapton, and so forth, we didn't hear even one good story about rock stars! But I guess that proves the old chestnut about the '60's: "if you were there you can't remember it."