How to… Shoot the invisible WORLD
From its earliest beginnings, photography has been used to help visualize the ‘unseen’ world; events that are too slow or too fast for the human eye to perceive, to record subjects that are visible only in areas of the electromagnetic spectrum outside the human range of sensitivity, or even capture subject detail that is too minute for the human eye to see. Different photographic techniques, some little used nowadays, can be used as a window into this invisible world. They can reveal how a bee might see a flower, how a drop of water disintegrates when it strikes a surface, or even the stress patterns created by the manufacturing process of plastic objects.
This article will look at some of the techniques used to do this, mostly readily available to photographers with a decent camera and flashgun, though infrared and reflected ultraviolet will require converted cameras and filters. Many of the skills will require improvisation, ingenuity, and experimentation, but all will certainly produce unique imagery…
THE ELECTROMAGNETIC SPECTRUM
The light that we humans see is just a very small part of the electromagnetic spectrum. There are a huge range of non-visible wavelengths, from gamma and beta rays, through to long-wave radio waves. Visible light (violet, blue, green, yellow, red) ranges from 400 nanometres (nm) at the violet end, to around 700nm at the red end. Beyond each of these extremes we have ‘invisible’ light; ultraviolet (UV) lights are the shorter wavelengths before the violet end, while infrared (IR) comes after the red end.
Ultraviolet has wavelengths from 400 down to less than 200nm, though for photographic purposes a wavelength of around 365nm will be most useful. UV
