A rainbow with no rain.

More years ago than I care to remember I bought a “Rainbow Disk”.  It’s a 6-inch diameter circle of clear, flexible plastic. It’s a “hologram replica diffraction grating”, and was made by a long-defunct Californian company called “Fluid Forms Inc”.  If you look through it highlights break up into spectral colours.  If point light sources reflect off its surface the reflections are also of spectral colours.

The packaging is very much of its time!

Here are my five office ceiling lights taken by shooting through the disc.  You can see the spectral colours as well as the normal colours.

You get a more abstract look by shooting the reflected spectral colours.  Here I’ve used an adapted Pentax 110 70mm lens on my OM-1 Micro Four-Thirds body.  By choosing a background not lit by the sun I’ve got a good brightness separation between the background and the colours.  I’ve also edited the image in Affinity Photo to increase the colour contrast.

Changing the shape of the flexible disc gives a different pattern, as does changing its angle relative to the light source.

This last image has a bit of the background, leaves from a Japanese Maple tree, to add some extra shapes and colours to the foreground spectral lines.

It’s a fun thing to play with, and is about the age of my Pentax 110 lenses, so it’s good to see them being contemporaries again.