Photography

Category: Pages
Published: Sunday, 11 March 2018 07:54

Night photography

 Introduction

I have enjoyed photographing night creatures for over 35 years. With the rapid advancement in camera technology and LED illumination it is now possible to photograph birds flying at night and my techniques and equipment have evolved during those years. For this type of photography, the additional equipment can be as simple as a decent spotlight plus assistant or as complex as you wish. These are my thoughts and techniques as of September 2021.


Illumination

Photography in darkness requires either a continuous light source or electronic flash. There are several important differences between daylight and light sources which a night photographer needs to understand.

A fundamental of light is that the brightness of an illuminated subject, decreases in proportion to the square of the distance from the light source. For daylight photography, this fundamental can be ignored because the distance of the photographer does not change the brightness of the subject. When illuminated with artificial light, however, this is not the case as the diagram below illustrates. The diagram shows an object located at distance "d" is four times brighter than an object located twice as far away at distance "2d". Consequently, if the subject distance from the light source is doubled, the exposure needs to be increased by the equivalent of two f-stops and if it is halved, the exposure needs to be reduced by the equivalent of two f-stops.

 






Continuous lighting  - such as a spotlight is great for photographing stationary animals. Filament lamps and Xenon arc lamps produce light of excellent colour quality but are heavy and power hungry. LED spotlights and flashlights are portable, bright and energy efficient but most products produce light having poor colour quality. High colour quality LED lights with high colour rendering index (CRI)  are becoming available and produce excellent results at comparable prices.

Exposure is determined using the camera metering system by adjusting shutter speed, aperture and ISO. The Tawny frogmouth below, was lit with the car high beam with camera settings of 1/15s, f5.3 and 9,000 ISO.

 

Electronic flash - is the ideal portable light source because it emits an extremely intense burst of light that can freeze movement. Flash units contain complex electronics that produce a short electrical discharge inside a transparent tube and when sufficient light has been emitted, the discharge is terminated by the clever electronics. The flash-tube contains xenon gas which produces intense white light of very high colour quality. Most models have auto and manual modes which can be configured to produce  the correct exposure.

To illustrate the advantage of manual flash over continuous light sources in freezing motion, I photographed an operating ceiling fan, with black lines painted on one blade, at different shutter speeds and with different flash power settings. Images in the top row were taken using a spotlight and camera shutter speeds from 1/500s  to 1/4000s. The bottom row was taken using a fixed shutter speed of 1/200s on power settings from full power to 1/32 power. Comparison of the images reveals that 1/4,000s shutter speed is equivalent to a flash power setting of 1/4 and the 1/32 power setting is estimated to be equivalent to a shutter speed of 1/20,000s.


Flash extender - Combined with a telephoto lens at night, a fresnel lens located in front of the flash concentrates the light output.To illustrate this, the images below were taken with a 50mm lens with identical conditions and processing.The the beam angle is reduced to produce a small 'hotspot' with a 3 f-stop gain in brightness.


 

Focusing at night

The focus sensors in DSLR and mirrorless cameras essentially measure subject contrast and adjust the focus distance to achieve maximum contrast. Illumination intensity, subject contrast and movement, each effect the camera's ability to focus accurately and quickly at night. High intensity illumination is required to obtain fast and accurate focus.

LED flashlights provide sufficient light output to focus well on stationary subjects at night, however flying birds require lights of much higher brightness. The human eye is a poor judge of intensity and what may appear bright to the photographer may in fact be photographically dim!


Exposure determination

With continuous light sources, obtaining the correct exposure is identical to daylight photography.

Using flash, the task is more difficult and is dependant upon equipment and settings. With my Nikon D750 camera, good results are obtained using a Nikon SB-800 flash on a manual power setting. With my Nikon Z6ii and TTL fill flash excellent results with stationary subjects can be obtained from 5m to 50m distance.

At the commencement of a night outing, I "calibrate" my  setup by taking a few test shots of an object such as a tree trunk, at what I consider to be a typical distance.

 

Gear for night

When working from a car or with an assistant, photography in the dark is straightforward. When alone, simple tasks including, changing settings, and adjusting gear are difficult and error prone. It is a great help to pre-configure as many settings as possible and get your gear ready before nightfall. My setup shown below  includes a carbon fibre bracket, rechargeable spotlight and TTL cable which weighs 750g. On maximum power, the spotlight produces 700 lux at 10m distance, which makes it possible to focus on birds flying at night at distances of at least 20m.

 
 

Tripod - A tripod is a useful adjunct for photography at fixed locations such as perches, roosts or nests. A small lightweight carbon-fibre tripod can support the camera or  be used as a stand for an off-camera flash is useful.

Off camera flash - Occasionally, I use sync. cables or Pocket Wizzard Plus-X radio triggers to fire flashes located away from the camera. Previously, I used Nikon's 'CLS' system but found it time consuming to set up and unreliable due to unseen beam path obstructions from unseen foliage in the bush.

 

Camera settings

Settings Banks - Many cameras allow you to save your favourite settings for quick recall. I have pre-configured settings for night photography which I can select by simply rotating a knob.

Image format - RAW file format has high dynamic range and a high capacity for setting white balance and salvaging shots which would have been spoilt by over or under exposure had they been taken in jpeg format.


LCD Monitor/viewfinder - At night display screens appears much brighter than during the day and images which appear adequately exposed are often significantly underexposed. To counteract this, I turn the monitor brightness right down and where possible check the image histogram.

 
Shooting Mode - I set my camera to manual mode for outdoor night photography.


Focus - For stationary birds I use the centre autofocus point with the camera set for 'backbutton continuous autofocus'. Backbutton focus makes it easy to reframe the subject without  refocusing. For flying birds, I use continuous autofocus and multiple focus points. Different brands and models have a multitude of focus modes so you need to experiment to find which combinations work.


ISO - Producing sufficient light to properly expose the image or to obtain a 'motion-free' image can be difficult. Using higher ISO is equivalent to using a more powerful flash, however the downside is that image noise increases . On my camera ISO 800 produces an acceptable level of noise and I use that as my preferred setting.


Aperture - A wide aperture is often desirable to isolate the subject from the background and increase the maximum working range of the flash. The downside is that accurate focus is critical and most lenses are softer at their widest aperture.


Shutter - The maximum shutter speed should be set no higher than the maximum flash sync speed of the camera. At night, the surrounds are dark and it is the short duration of the flash output which stops motion, not the shutter speed. I normally use a shutter speed of 1/60s when it is dark.

Very low shutter speed can be useful for stationary subjects to record ambient light as shown for the Barking owl below, which was taken at 1/15s. The owl remained sharp because it was exposed by the short pulse of light from the flash, whilst the background shows some blur from hand-held camera movement.

 


Illusion of speed - Flash combined with low shutter speed can be used
to give the illusion of speed. For the Nightjar below, a sharp image of the bird was produced by the the flash which is superimposed on a longer exposed image produced by the 1/30s shutter speed and focus light. By setting the camera flash mode to 'rear-curtain sync', the blurred image trails the bird giving the impression of speed.

 

 

This technique is a bit of a gamble as a potentially good image of a difficult to photograph subject, such as Grass owl with prey below, is ruined.

 

 

Nocturnal Eyes

Pupils - A continuous light always produces contracted pupils when the bird is looking toward it and there is no way to prevent that. This is especially noticeable for a bird having a light coloured iris such as the young Boobook owl on the left below. Large eyes are a prominent feature of nocturnal birds and if we were able see in the dark we would see that their pupils are always wide open. To me, dilated pupils look natural and can be captured by pre-focusing then turning off the focus light before releasing the shutter, as shown for the image on the right.

 

Red-eye

Red-eye occurs when the light source is located 'close' to the camera and light reflected from the retina enters the camera lens. By moving the light source away from the camera or moving closer to the subject, red-eye can be reduced and often avoided. This is illustrated in the diagram and images of a Tasmanian Boobook owl below, which were taken at different distances and head angles. Increasing the lens/flash angle can be achieved via a camera bracket or 'off-camera' flash.


 

Red-eye correction

Sometimes you cannot avoid red-eye as seen in the left and centre images above, however it can often be 'fixed' by photo-editing. Pupils almost always have some light and colour, 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 eye reflections to enhance their appearance as shown for the same images below. A single light source often produces multiple catchlights due to reflections from the cornea and eye lens.

 

 

Flying birds

Flying birds present the ultimate challenge. Sharp images can be obtained by shooting a bird leaving or arriving at a pre-focused destination or by achieving focus in flight. The Tawny frogmouth below, was taken by pre-focusing on a perch it was hunting from and watching with a dim red light until it flew. The Grass owl was focused in flight using one of the camera brackets above.

 Conclusion

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