Ultraviolet Fluorescence



Ultraviolet light (UV) is invisible to the human eye but when certain substances are exposed to it, they emit visible light which we can see. This phenomenon is called fluorescence. I became interested in photographing fluorescence when a friend told me that scorpions appear bright 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, in addition to producing UV also emit coloured visible light and cameras often render reflected UV as unwanted colour. I made the equipment described below to prevent false colours appearing and a selection of images showing fluorescence are shown below.

The essential components of my UV lamp, were purchased in 2018 from ebay for around AU$50 and include:

  • 10 watt 365nm UV LED. High output power of the LED reduces photographic exposure times and LEDs having wavelengths up to approximately 400 nanometres also work well.
  • Filter to block visible light emitted from the LED. This filter appears black but is transparent to UV. I used a "ZWB2" filter. This filter and a good UV led are the most important components needed to obtain good photos.
  • Resistor and heatsink to limit the maximum current and stop the LED from overheating
  • 3.6 volt rechargeable lithium cell, charger and switch
  • Condenser lens on the front of the lamp concentrates the UV into a brighter more intense beam which makes the fluorescence look more vibrant and reduces exposure times
  • To prevent unwanted ultraviolet light from reaching the camera sensor you can use a UV blocking filter on the camera lens. Many cameras record UV as colour and UV filters sold as "lens protectors" often do not block the longest ultraviolet wavelengths. A "UV(0)" or "L39"  filter stops nearly all reflected UV appearing as false colour in the image


UV lamp


Lens filter - Aluminium  foil, UV exposure for 20 seconds, f16, Nikon D750 with and without a suitable filter


Marbled scorpion - UV exposure for 6 seconds at f16 and fill flash. Nikon D750, 180mm lens with extension tube and tripod


Fledgling Powerful owl feather (left) and Sulphur-crested Cockatoo feather (right)


Diamonds and Rubies


 Australian $5 note




Lichen growing on sandstone





Photographing Nocturnal Animals


I have enjoyed photographing night creatures for over 30 years and my ideas and equipment have continually evolved. With the rapid advancement in camera technology and the advent of LED illumination it is now possible to photograph birds flying at night. This trend will continue and the techniques and equipment I use today will quickly become outdated. For those interested in this type of photography the additional equipment that is needed can be as simple as a decent spotlight and an assistant or as complex as you wish. These are my thoughts and techniques as of August 2018, which I hope will provide insight and tempt you to venture out at night and enjoy your photography in a different light.


Photography in darkness requires the use of artificial light in the form of either a continuous light source or electronic flash. There are several important differences between daylight and light sources which the experienced night photographer understands and is familiar with.

A fundamental characteristic of light is that the intensity (brightness) of light reaching an object, decreases in proportion to the square of the distance from the light source. The diagram below shows that if an object is located at "d" it would be four times brighter than if it was located at "2d". Each time the distance to the light source is doubled, the photographer needs to increase the exposure by the equivalent of two f-stops. Likewise, if the distance is halved the exposure needs to be reduced by the equivalent of two f-stops.

For outdoor photography during daylight, the sun is so far away from Earth that the brightness of an object effectively does not vary with distance and this characteristic of light can be conveniently ignored. However, a photographer on Mars which is 1.5 times further away from the sun, would need to increase the exposure by the equivalent of one f-stop.

Continuous light - is great for photographing animals that are stationary. Filament and Xenon arc lamps produce light of good colour quality but are power hungry and not very portable. LED lights are portable, bright and energy efficient  but most models produce poor colour quality. LEDS's with high colour rendering index produce high quality colour and are starting to  appear in higher-end units. With continuous light, exposure is determined using the camera metering system by adjusting shutter speed, aperture or ISO. The Tawny Frogmouth below was sitting on a fence post and I used the car headlights for illumination and the camera to determine an exposure of 1/15s at f5.3 and 9,000 ISO.

Electronic flash - the ideal portable light source. Flash units contain complex electronics that produce an electrical discharge inside a transparent tube. When sufficient light has been emitted to produce the 'correct' exposure the discharge is terminated. The flash-tube is filled with xenon gas which produces intense light having a colour comparable with midday sunlight. Most models have an auto mode, however I prefer one that also has manual power settings which control the light output in f-stop increments.

The composite image below shows a series of photos of an operating ceiling fan. One blade was painted on the edge with white paint and black lines. Images in the top row were taken using continuous light and show the effect of camera shutter speed in stopping motion. The bottom row, taken using an electronic flash on different power settings at a camera shutter speed of 1/200s, illustrates the superior motion stopping ability of electronic flash. Comparison of the images also reveals that the maximum 1/4,000s shutter speed on my camera is equivalent to a power setting of 1/4 and the motion stopping ability of the 1/32 power setting is equivalent to a staggering shutter speed of around 1/20,000s.

Flash extender - a Fresnel lens placed in front of the flash is a useful aid to a telephoto lens at night. It concentrates the light into a narrow beam, typically providing a 2-3 f-stop increase in light intensity. To illustrate the benefit, the images below were taken using a 50mm lens with identical camera/flash settings and image processing


Focusing at night

The various types of focus sensors used in DSLR cameras essentially measure subject contrast. The camera continually adjusts the lens focus until maximum contrast is obtained at the focus point indicated in the viewfinder. Illumination, subject contrast and movement, independently affect the cameras ability to focus accurately and quickly. At night, additional illumination is required for the system to work efficiently.

LED flashlights and spotlights provide sufficient light output to focus on stationary subjects, however flying birds require very intense illumination to enable the camera to rapidly achieve focus. A fast telephoto lens is also helpful as it increases the amount of light received by the autofocus sensors, making the cameras task easier. I believe that red light is ideal for watching and focusing on stationary animals because nocturnal eyes have very poor sensitivity to red light, which therefore causes minimal disturbance.

Exposure determination

Obtaining correct exposure with a continuous light source is achieved using the camera metering system. Auto-flash (TTL) relies on the camera in conjunction with the flash unit to determine when to terminate the light output. Auto-flash, like a camera in full auto mode, does not compensate for variation in subject contrast or background brightness and outside at night auto settings often produce disappointing results. For this reason I prefer using flash on manual power settings.

Prior to a night outing, I "calibrate" my camera/flash set-up by taking test shots of an object such as a tree trunk, at a known (estimated) distance. With my favourite flash unit set on 1/4 power and camera on ISO 800 I achieve good range and motion stopping ability. Next I calculate a working guide number which I record on a piece of white tape on my flash extender for quick reference. For example, if the best test shot of a tree trunk 5m away was f16, my working guide number, is 5m x 16 = 80 metres. This working guide number is correct only for the setup for which it was calibrated!

To photograph a subject 10 meters away, I can simply divide the working guide number by the distance ie 80/10 to get f8. If I prefer to use f5.6 instead of f8, I would need to either reduce the light output from the flash by one f-stop, by reducing either the power setting or reduce the camera  ISO. Providing, my estimate of the the subject distance was reasonable, the first exposure is usually quite close to the mark.


Gear and handling

When working from a car or with an assistant, photographing an animal in the dark is pretty straightforward. When you are alone and in darkness, simple tasks such as changing equipment  settings and trying to manage lights and other gear is difficult and error prone. If you work alone as I usually do, it is a great help to simplify your setup and pre-configure as many equipment settings as possible to minimise lost opportunities. My general setup is shown below on the left and incorporates an 80-400mm zoom lens, camera bracket, flash with flash extender, and focusing lights. It is simple and robust and makes working in the dark easy. For flying birds I use the set-up on the right which includes camera bracket, very intense focus lights and a fast 180mm f2.8 lens.

Tripod - A tripod is useful for photographing subjects at fixed locations such as roosts or nests. I have used a small lightweight carbon fibre tripod to support my camera or as a stand for an off-camera flash.

Slaves and triggers - Occasionally I use off-camera flash triggered by sync. cables or  Pocket Wizzard Plus-X radio triggers which are usually reliable. Previously  I have used Nikon's clever inbuilt 'CLS' system which employs line-of-sight infrared signals between flash and camera, however it is time consuming to set up and very unreliable in the bush due beam path obstructions from leaves, branches and unseen objects.




Camera settings

Settings Banks - Many cameras allow you to save your favourite settings for quick recall. My camera has two banks which I have configured for night use, one for flying birds and one for stationary subjects. It saves enormous time and frustration when working in the dark to be able to select your settings simply by rotating a knob.

Image format - RAW file format has a much higher capacity for correcting white balance and for salvaging great shots which would have be spoilt by over or under exposure if they were created as JPG files.

LCD Monitor - At night the monitor screen appears very much brighter than it does during the day and often images which look adequately exposed are considerably underexposed. For night work I turn the monitor brightness right down and for important shots I also check the image histogram to make sure the exposure is OK.

Shooting Mode - My camera is always set to manual mode because I always use flash at night.

Focus - For stationary birds I use a single central focus point with continuous autofocus. I have the camera set up to focus using the 'backbutton' which makes it easy to reframe the subject without  refocusing. For flying birds I use continuous autofocus with multiple focus points selected and use the shutter button to focus and to shoot. Camera brands and models have a multitude of focus modes and I am not sufficiently knowledgeable to expound on which ones are the best.

ISO - Producing sufficient light to properly expose and obtain a 'motion-free' image at night can be difficult. Using high ISO is equivalent to using a more powerful flash unit, however the downside is that it also increases image noise. ISO 800 produces an acceptable level of image noise on my camera (Nikon D750) and I use it as my go-to night setting.

Aperture - Using a wide aperture is desirable to isolate the subject from the background and increase the maximum working range of the flash. The downside is that accurate focus is more critical and some lenses are soft when used wide open.

Shutter - When using flash and a DSLR with focal plane shutter, the maximum shutter speed should be set no higher than the maximum flash sync speed, which is around 1/200s for many models. At night, the surrounds are usually dark and it is the short duration of the pulse of light from the flash which stops motion, not the shutter speed.

Slow shutter speeds can be useful for stationary subjects to record ambient light detail as shown for the Barking owl below, which was taken at 1/15s. The owl remained sharp because it was exposed by flash, whilst the background shows some effects of camera movement.


Flash and low shutter speed can be combined intentionally to give the appearance of motion as shown for the nightjar below. The sharp image of the bird produced by the short duration of the flash is superimposed on the blurry 1/30s exposure resulting from continuous spotlight illumination. By setting the camera flash mode to 'rear-curtain sync',  the blurred part of the image can be made to trail the bird to give the impression of speed. 



More often than not though, an otherwise good photo of a hard to get subject, such as this grass owl with prey, is ruined!



Nocturnal Eyes

Pupils - Unfortunately, a continuous light always produces contracted pupils when the bird is looking toward it and this is especially noticeable with birds having a light iris colour as is apparent for the young Boobook owl below on the left. Large eyes are a prominent feature of nocturnal birds and if we were able see in darkness we would observe that their pupils are always dilated as shown for the adult Boobook on the right. Dilated pupils look far more natural to me and can be captured using electronic flash by pre-focusing the camera and turning off the focusing light several seconds before shooting.



Red-eye occurs when the light source is located close to the camera and light is reflected from the retina into the lens. It can be avoided by moving the light away from the camera or moving closer to the subject to increase the 'flash-eye-lens' angle. This is shown in the diagrams below and in the images of a Tasmanian Boobook owl, taken at different distances and head angles. Increasing the angle can be achieved via a camera bracket or off-camera flash. When red-eye cannot be avoided it can sometimes be removed by skillful photo editing, however, photos with red-eye often lack feather texture due to the flat shadowless illumination associated with a shallow flash angle.


Sometimes you cannot avoid red-eye as the images above show. When this happens red-eye can often be 'fixed' by careful photo-editing. Pupils almost always have some light and colour in them, so I prefer to darken them by 'burning' the shadows and mid-tones, then desaturating the colour until they are almost but not quite black. You can also 'dodge' the catchlights and other eye reflections to enhance their appearance as shown for the same images below.



Flying birds

Flying birds present a greater challenge to photograph especially at night. Images can be obtained by shooting a bird leaving or arriving on a pre-focused perch or by focusing on the bird in flight. The Tawny frogmouth below was taken by pre-focusing on the perch it was using and by watching it with a dim red light until it flew. The Grass owl was focused in flight using a camera bracket incorporating high intensity lights.



My thoughts and ideas should be viewed as a guide for those interested in night photography. They should not be considered as binding, rather as ideas and techniques that have worked for me. I hope this article can assist you in developing yours skills in photographing nocturnal creatures at night and encourage you to give it a go.



Observing Nocturnal Animals

Night observation is very different from observation during daylight. At night we rely on our sense of hearing combined with sight and artificial light to locate animals. Nocturnal animals have acute senses compared to us and they are usually aware of our presence long before we see them. Often I find an animal by its call or the noise it makes as it moves, then I locate it by eye-shine.


Attraction aids

Many animals can be attracted by playing their calls and sometimes the calls of other species. Recorded calls are often used during owl surveys, by photographers and I  use them when looking for owls at new locations. Call playback can be highly disruptive and stressful to the animal if not used judiciously and I do not encourage its general use. Playback should be avoided near nest sites during the breeding season. Owls are strongly territorial so you should resist the temptation of divulging their locations to other photographers and twitchers, as they are sure to be harassed.



Vision is a complex sense which involves signals from the eyes which are interpreted by the brain. The retina at the back of the eye contain two fundamental types of light receptor cells, called cones and rods. Cones only work in bright light and rods only work in dim light. Diurnal animals including us have cone dominated vision which enables excellent perception of colour with high visual acuity in daylight. Most nocturnal animals have eyes with relatively few cones and an abundance of rods which makes for excellent low light vision but comparatively poor daylight vision. 

There are several cone types, each having a peak sensitivity to a different  light wavelength. The brain 'sees' colour not the eyes and it does this by combining the signals from each cone type, analogous to mixing primary paint colours to achieve all the colours of the rainbow. The more cone types a species has, the better its ability to distinguish colours. Mammals have either two or three cone types whilst birds, reptiles and fish have four, which provides them with superior colour perception and the ability to see ultraviolet light.

The diagram below shows the colour sensitivity of the three types of cone cells in the human eye.

In very dim light the cone cells don't function and the brain receives signals from the rod cells only, which for nocturnal animals, enables excellent low light vision . There is only one rod type however, which means there is no perception of colour in very dim light, which is why we can't see colour outside at night even on a full moon. The graph below shows the spectral sensitivity of rods in the human eye (400-600nm) and reveals why rods are completely insensitive to red light (620-680nm). The significance of this is that you can use red light for watching most nocturnal animals without spoiling their night vision or causing them excessive disturbance. Most can see red light however, if it is directed at them because their eyes do contain red senstitive cones.



White light

White light is great for finding animals but is not suited to studying nocturnal behaviour or watching nesting owls. White light has the advantage that we can see the true colour of an animal's eye-shine, which can be useful for identification at distance. During a holiday in Sabah, Borneo, I heard a creature on the forest floor in the grounds of the hotel I was staying and with the aid of a LED torch, I located it by its beautiful blue eye-shine (below). It was a Mouse deer, not much larger than a rabbit. White light can cause temporary night blindness lasting at least 10 minutes, during which time the animal could become susceptible to predation of prevent it from feeding.



Red light

Rods don't see red, so for observing animals at night, headlamps that use red LED's are ideal. Red light does not disrupt an animal's night vision or your own. My favourite headlamp below, comprises a lens, a 3 watt red LED, a resistor to limit the current, a switch and a 3.7 volt rechargeable battery. It can be attached to a tripod and the beam can be focused or spread to control the width and brightness. The main disadvantage of using red light is that everything appears red.



With red light, you are able to watch and photograph nocturnal animals behaving naturally. The photo below of a nesting Powerful owl was a 1/3 second exposure at f6.3 and ISO 6400 illuminated with the headlamp shown above. I observed this nest for many years using red light and the owls were always aware of my presence but were unconcerned. I watched this adult leave the hollow on dark and return a short time later with a Ringtail possum to feed its young. If white light was used, it probably would not have returned whilst I was watching or it may have abandoned its nest.




Walking at night

Long-sleeved shirt, long pants and sturdy boots are essential  to protect yourself from cuts, scratches and bites when walking in the bush at night. I prefer to walk along tracks rather than through bush because you can move quietly and are likely to see many more animals. Depending on the weather and where I am walking, I may also take extra clothing, food, water, insect repellent, first aid kit and something to sit on. Unnecessary gear can turn a casual walk into a hard slog so I try to carry only the essentials.

Being in the bush by yourself can be very rewarding and you usually locate more animals when you are alone because your senses are heightened, however you need to be better prepared. In the dark your vision and sense of direction is poor and it is easy to become disoriented or fall on something you didn't see. When I venture out alone I always:

·     Tell someone where I am going and when I expect to return

·     Know my exact location at all times and if unsure, stop until I have worked it out

·     Stay on the intended route unless I am familiar with the area or am carrying  navigation aids

·     When I venture off-track I always watch where I place each footstep to avoid a fall.


Richard Jackson



As a child I grew up in the northern suburbs of Sydney with Ku-ring-gai Chase National Park as my back yard. After school and on weekends I would spend countless hours with my best friend and school mates exploring the bush, catching tadpoles, yabbies and cicadas, damming creeks and playing hide and seek.


During those years I developed a love for the bush and became interested in the various birds and mammals that lived around me. I was always fascinated by the wonderful wildlife photos in National Geographic magazine and was in awe of the SLR film cameras advertised on the back pages. My passion for nature photography started at age fourteen when my parents bought me my first camera, a Kodak Instamatic. Dreams of magazine images were shattered when my first roll of film was developed and the beautiful Robin I photographed in my mother's rose garden appeared as a scarlet speck.


By age seventeen I had saved enough money for a Nikon F2 camera and 300mm lens which my father purchased for me, duty-free. Without success in achieving the stunning images I dreamed of, my interest in wildlife photography faded until after my first child was born. It was then when free time was so scarce, I decided one night to venture into the Royal National Park, near my home in Engadine, to see if there were any animals about. To my surprise and delight I saw possums and watched a Tawny Frogmouth fly up to a dead limb, close enough for me to photograph.


After overcoming my fear of the dark I quickly started to enjoy the solitude of being alone in a world of nocturnal creatures and the uncertainty and excitement of what I may find. With the advent of affordable digital cameras with fast and accurate autofocus it became much easier to take quality images at night and I now look at my prized photos from the past and keep them as momentos.


My main photographic interest is in owls and nocturnal mammals and therefore I love nothing more than heading into the bush when most people are calling it a day. As the sun sets a world few are aware of awakens, where I observe creatures that most only see in books.


I owe my continued interest in this hobby to Julie my wife for her loving support and ongoing encouragement for over thirty years. Thank you to Gerard Satherly who built this website for me and to the friends I have made at Feathers & Photos Bird forum who have taught me so much about photography.


I hope you enjoy my photos and if you would like to contact me my e-mail address is prsj56[at]optusnet.com.au