What is UVIVF photography?

Ultraviolet-Induced Visible Fluorescence (UVIVF) is a process in which given wavelengths of ultraviolet radiation are absorbed by a material’s molecules, causing them to achieve an excited state. Through this, fluorescent materials reach an unstable excited state and lose small amounts of energy through other mechanisms until they can drop to a suitable ground state by releasing a photon of a specific energy and wavelength. Since energy was lost before the remainder was released as a photon, the wavelength of that photon is longer than the stimulating source, which means an ultraviolet light is able to produce dramatic visible fluorescence.

This phenomenon is commonplace enough that everyone has likely seen it in some fashion. The way a white T-shirt glows blue under a blacklight, the way a piece of printer paper gets bright in the sun, and even fluorescent light bulbs all result from the same process. The main difference is the subject and intensity of the ultraviolet light source.

Though a camera can see some ultraviolet, a normal camera has a built-in filter which blocks the great majority of infrared and ultraviolet light. By using a light source with a wavelength shorter than 400nm, one can eliminate most of the ultraviolet, allowing just the fluorescent light to create an image. This means that all the light in the photograph is originating from within the subject itself!

Is this how bees and butterflies see light?

TL;DR explanation:
UVIVF images are not the same thing bees see, but there is overlap with the what they can sense. Nothing short of being a bee will allow us to truly comprehend how they perceive the world because our senses and theirs differ too greatly. If you consider that two people, one with normal color vision and one with deuteranomalous color vision, can never truly understand what the other sees, it is clear that trying to do the same for another species is impossible.

Full explanation:
While there is not one-to-one correlation between UVIVF photography and the way butterflies and bees see light, there is some crossover between their vision and UVIVF photography.

Butterflies, bees, some birds, and even reindeer are able to  see ultraviolet light reflected by objects they are looking at in addition to whatever portion of the visible spectrum they are capable of sensing. Honeybees for example do not see red light which tells you that red flowers are likely intended for other pollinators such as birds or beetles.

In contrast, well-done UVIVF photography actually must reject as much ultraviolet light as possible from the camera’s sensor, instead imaging strictly the visible light emitted from the subject in response to ultraviolet stimulation. Ideally, no UV is recorded in the image, leaving the taken photo completely composed of visible (blue through red) light.

There is major crossover between UVIVF and reflected-UV photography, such as flowers’ nectar guides and pollen absorbing UV. Where in reflected-UV imaging these features appear black or dark, there’s a high probability that it will either fluoresce a different color or very intensely (since in order to fluoresce, the UV must be absorbed and not reflected.)

Since my work uses a narrow band of ultraviolet light centered on 365nm, there is a great deal of potential reflection/fluorescence that is going unrecorded, but the depiction of UVIVF imaging allows viewers to imagine how bees might perceive light even if it does not directly represent it. If you consider further that these insects see through compound eyes where we see through a single lens and that they can perceive the polarization of light where we can’t, it becomes clear that there’s no explicit way to represent the world exactly the way bees sense it. That said, there is a whole separate genre of photography dedicated to accurately recording the same wavelengths of light bees and butterflies can sense (and I believe that the two combined come closer to representing true pollinator vision than either alone.)

Furthermore, there is ongoing research into how fluorescence affects pollinator (and prey) relationships, taking for example a study in which blue fluorescence removed from carnivorous plant traps reduced the amount of prey caught. Other studies have demonstrated that bees are generally more attracted to green and pure blue light with one study discovering this by offering sugar at a plain blue marker and another blue marker dyed with a blue fluorescent compound.

Looking at specific cases such as Helianthus flowers, under ultraviolet light the florets glow bright blue in a field that is otherwise ‘bee-black.’ The majority of orchids have blue fluorescence centered on the reproductive anatomy and all Phacelia appear to exhibit vivid green-white fluorescence at their centers, all of which suggests that fluorescence is playing a role in pollinator attraction. Most intriguingly, Sarcodes sanguinea, a mycoheterotrophic plant whose only above ground appearance is a solid red-stalked bloom, has striking blue fluorescence inside the flowers. While the red coloration implies that bees are not a targeted pollinator (as bees cannot sense red light), yet they have still been observed visiting these flowers and it seems likely that the blue fluorescence is playing a part.

What equipment do you use for UVIVF photography?

For UVIVF I use 365nm LED light sources. It is possible to use any wavelength of ultraviolet, such as a common 395/405nm light, but you would need to take the camera’s sensitivity, and your own body’s sensitivity into account. For anyone looking to try the technique themselves I recommend purchasing a Convoy S2+ with Nichia LED and some form of UV-bandpass filter such as Schott UG11 or Hoya U340.

What is false-color infrared photography?

False-color infrared photography is done using a modified camera which has the built-in filter removed and replaced, allowing the sensor to record in its full range of sensitivity. Since cameras are only made to photograph red, green, and blue light, the infrared light has no specific color it should be in the camera. Instead, the infrared is unevenly mixed into those 3 colors, which creates a colored impression of infrared light, hence being called ‘false-color.’ By exploiting this characteristic of digital cameras, one can greatly influence the way infrared light should appear, whether blue, green, pink, or yellow, some of the most common colors for infrared in this type of photography.