Ultraviolet Fluorescence
Ultraviolet light (UV) is invisible to the human eye but when certain substances are exposed to it, they emit visible light. I became interested in photographing fluorescence when a friend told me that scorpions appear blue under UV. People rarely see scorpions because they are brown and well camouflaged but they are quite common where I live on the outskirts of Sydney and are easy to find at night by searching the leaf litter with a UV lamp.
My initial photos were disappointing because the backgrounds looked artificially coloured. I discovered that most ultraviolet sources, also emit visible light and cameras often show this visible light and reflected UV as unwanted colour. I built the lamp below to prevent false colours and I also use a "UV(0)" filter on the camera lens to prevent reflected UV light from reaching the camera sensor. My UV lamp and a selection of images exposed using UV and visible light are shown.
The lamp was built for less than AUD $100 and includes:
- 10 watt 365nm UV LED
- A black "ZWB2" filter inserted beneath the LED and lens to block unwanted visible light emitted by the LED
- Condenser lens on the front of the lamp to concentrate the UV into an intense beam which makes the fluorescence look more vibrant and reduces exposure time
- Resistor and heatsink to prevent the LED overheating and to limit the maximum current
- Rechargeable 3.6 volt lithium cell
UV lamp
Diamonds - visible and UV light
Marbled Scorpion - UV exposure for 6 seconds at f16 and fill flash. Nikon D750, 180mm lens with UV0 filter, extension tube and tripod
Feathers - Fledgling Powerful owl feather and aSulphur-crested Cockatoo feather exposed with visible and UV light
Australian $5 note - visible and UV light
Eggs - visible and UV light
Lichen growing on sandstone - visible and UV light
Dahlia flowers - visible and UV light
