Images of Invisibility

Images of Invisibility
by Bj�rn R�rslett




� Bj�rn R�rslett/NN (June, 2000)

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Take away all of the visible band of the light spectrum. Still, about 50% of the energy from the sun reaches Earth, and a large fraction of this non-visible radiation is capable of forming a photographic image. I've been preoccupied with the potential of combining the UV and IR bands to give a completely "invisible" image, and the Nikon D1 camera has given me the means to obtain that end. Needless to say, these images are not easy to relate to the visual impressions we are familiar with. Undoubtedly, they expand the pictorial potential of the D1 digital camera. I have tried to make similar images using my F5 camera and EIR colour film, but getting an equally pleasing colour rendition seems very difficult indeed. So far, I haven't had much success followingt the film-based approach.

All images shown on this page were obtained at Summer Solstice, 2000, using the UV-Nikkor 105 mm f/4.5 lens with a filter pack consisting of the Nikon FF black UV-transparent filter in conjunction with the Tiffen Hot-Mirror filter. The latter is necessary to balance the IR sensitivity of D1 to better match its UV response. I set D1 to "sunny" colour balance and dialled in a +1 stop correction, otherwise I just put my D1 on auto exposure. Exposures ranged from 1/8 to 1 seconds at f/11 under slightly hazy skies. The resulting NEF files are processed with the Nikon Capture program by selecting "Auto" colour balance there. Some additional tweaking in the blue band provided better image detail in several cases. The green band is recorded at much lower level than the red or blue band, so subsequent noise removal in Photoshop often is necessary. The way in which different subject areas reflect UV and IR gives rise to a quite rich colour palette ranging from light blue to deep reddish hues. Water surfaces frequently record as pastel hues, in sharp contrast to their typical dark IR rendition. This clearly is caused by reflected UV. Expectedly, little green is shown but sometimes, quite yellowish hues may occur.

Although I employed my UV-Nikkor to refine my technique for taking "invisible" images, I have sucessfully pressed other single-coated lenses into service to obtain these images. The basic problem then, however, is an unavoidable increase in exposure time. You have to experiment with available gear to find your own, optimal setup.

For an updated review of digital UV and IR photography, click here.

Last Update 1 October, 2002