Limits on the wavelengths represented in ultraviolet images lepidoptera

Ultraviolet (UV) imaging is commonly used in the study of plant and animal coloration, especially for visualizing the size and shape of UV reflectance patterns in butterflies and moths. We show that the spectral emission of light sources and the transmission spectra of the lenses and filters often used to make such images are not flat in the UV. As result the images are made with a narrow range of UV wave-lengths as small as 360-390 nm in an inexpensive system with typical components. This limit on the wavelengths represented in the images can lead to various measurement errors that must be considered in using such images to characterize and study UV coloration.