Photography

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Published: Sunday, 11 March 2018 07:54

Night photography

I have enjoyed photographing night creatures for nearly 40 years. With the advancement in camera technology and lighting it is now possible to photograph birds flying at night.The additional equipment required for wildlife can be as simple as a decent camera with a focus-light and an assistant. When working with an assistant or working from your car, night photography is fairly straightforward, however when alone and outside it is beneficial to pre-configure as many camera settings as possible.

The techniques and equipment I use have evolved over many years and should be considered as a guide to be improved upon (updated 2023-12-01).

 

ILLUMINATION

Photography in darkness requires either a continuous light source or an electronic flash. There are several important differences between daylight and artificial light sources.

A fundamental of light is that the brightness of an illuminated object, decreases in proportion to the square of the distance from the light source. For natural light photography this can be ignored because the light source is so far away from the subject that the brightness is virtually constant. With artificial illumination this is not true, as the diagram below illustrates. If the distance is doubled, the exposure needs to be four times longer or the aperture needs to be two f-stops wider.

 

 

Continuous sources such as high CRI (colour rendering index >80) flashlights, Xenon arc lamps and old-fashined halogen spotlights produce light of excellent colour quality.

Exposure is determined using the camera metering system as normal; by adjusting shutter speed, aperture and ISO. The Tawny Frogmouth below, was illuminated using the car's headlights, with camera settings of 1/15s, f5.3 and 9,000 ISO. The main disadvantages of continuous light compared to flash, is the relatively low intensity and the inability to freeze fast moving subjects.

 

 

Electronic flash is the ideal light source for freezing fast motion because it emits a short burst of intense light, however the downside compared to continuous light is that additional light is required for the camera to autofocus. Most flash units have manual settings of  full power, 1/4 power, 1/8 power, 1/16 power and 1/32 powers which is equivalent to using shutter speeds of approximately 1/250s, 1/4000s,1/8000s,1/16000s and 1/32000s respectively. This is illustrated in the image below of an operating ceiling fan photographed at shutter speeds from 1/500s to 1/4000s and flash power settings from full power to 1/32 power.

Properly exposed images can be obtained using manual power if the subject distance is known or by using 'TTL mode' (through-the-lens) as shown in the series of images below, taken at decreasing camera-subject distances.

 

In TTL mode and the camera set to front curtain sync, a pre-flash is fired just before the camera shutter opens which allows the camera to calculate the amount of power needed for correct exposure. The pre-flash cannot be seen because it is fired approximately  50 milliseconds before the main flash. Flash exposure compensation is usually necessary and at the commencement of an outing, I check my setup by taking several shots of an object such as a tree trunk, to align the flash head and to determine the amount of flash exposure compensation needed.


 

 

FOCUSING

Autofocus sensors in general adjust the focus distance to achieve maximum contrast on the image sensor. Illumination intensity, subject contrast, motion, the type of camera and the particular camera/lens combination effect the ability to focus quickly and accurately. Mirrorless cameras have auto-focus systems quite different from DSLR's and even flagship mirrorless cameras (2023) have trouble acquiring focus when a deep red focus light is used.

A small flashlight can provide sufficient light to auto-focus (AF) on stationary subjects, however flying birds require far higher brightness. The human eye is a poor judge of brightness and at night what appears bright is often too dim to focus on a flying bird.

 

GEAR

A summary of the cameras, lenses and  electronic flashes I have used is shown below.

1974-2004 (film era and manual focus equipment) Nikon F2/Nikon FM2 with 'Nikkor 300mm f4.5', 'Sunpack Auto 455' electronic flash and Kodak ISO 200 colour film.

2004-2010 Nikon D70 (6 Megapixels) with 'Nikkor 70-300 f4.5-5.6' AF lens and 'Nikon SB-800' flash. This gear was a huge improvement on manual focus cameras and film.

2010-2012 Nikon D90 (12 Megapixels) with 'Nikkor 70-300 VR', 'Nikkor 80-400 VR' and  'Nikon SB-800' flash.

2012-2015 Nikon D7000 (16 megapixels) with 'Nikkor 70-300 VR AFS', 'Nikkor 80-400 AFS VR' and 'Nikon SB-800' flash. Better autofocusing enabled photography of birds flying at night.

2015-2021 Nikon D750 (24 megapixels) with 'Nikkor 180mm f2.8', 'Nikkor 80-400 AFS VR' and 'Nikon SB-800' flash. 24 megapixel full frame camera produced fantastic image quality and better results all round.

2022-2024 Nikon Z6ii (24 megapixels), Nikon Z8 & Nikon D850 (45 megapixels)  with 'Nikkor 100-400mm zoom,  300mm and 500mm primes and Nikon SB-800 flash. Mirrorless cameras are a joy to use at night because the viewfinder can  see clearly in almost total darkness. For birds flying at night I use the D850 with 300mm f4 lens in conjunction with a  deep red (660nm) red light.

 

Flash extender - consists of a Fresnel lens placed in front of the flash window, which concentrates the light output. It produces a 'hotspot' with a 3-4 f-stop gain in brightness and is very useful in conjunction with a telephoto lens. The images below were taken with a 50mm lens using identical exposure and processing, without and with a flash extender.

 

Focus lights A white focus light works well but I have found flying birds often try to evade a bright white light, making it difficult to focus. Red light (660nm) with DSLR PDAF autofocus works very well  and induces minimal evasive response. Green light (550nm) is ideal for focusing mirrorless cameras on stationary subjects but works poorly on flying birds which try desperately to evade it.

Coloured lights are problematic in that a strong colour cast, which  can be difficult to remove in post processing, is often present in the shadows of the image. To minimise this problem I use the circuit below in conjunction with the flash set to manual power, to turn the focus light off for approximately 1/20s the instant that the flash fires.

The benefit of the circuit can be seen by comparing the two images below which were taken using the same exposure (f5.6 1/90s ISO 2200). In the image on the left the circuit prevented most of the green light from appearing and the image on the right side was taken with the circuit disabled.

 

 

  

Flash brackets can be used to minimise 'Red-eye'. A home-made carbon fibre bracket and a green focus light incorporating the 'momentary circuit', is shown below

 

 

Tripods are useful when slow shutter speeds are required at fixed locations such as perches, roosts or nests. A lightweight tripod can support the camera or be used as a stand for an off-camera flash.

 

Off-camera flash - I use 'Pocket Wizzard' radio triggers to fire flashes located off-camera. Other systems such as Nikon's 'CLS' system or sync. cables  are less reliable and time-consuming to set up.

 

CAMERA SETTINGS

Settings Banks - Many cameras allow you to save your favourite settings for quick recall, which is very useful at night.

Image file format - RAW files have higher dynamic range and great capacity for salvaging images taken with non-optimal camera settings.

LCD Monitor/viewfinder - Display monitors appear much brighter in the dark and images which appear adequately exposed are often underexposed. To counteract this at night, I turn the brightness down and occasionally check the image histogram.

Shooting Mode - I use manual camera settings and either TTL or manual flash power settings.

Focus - For stationary birds I use the centre autofocus point with the camera set for 'back-button and continuous autofocus' which makes it easy to recompose the image without having to refocus. For flying birds, continuous AF and multiple focus points works well. Today's cameras have countless autofocus modes which need to be explored to discover which work the best.

ISO - Producing sufficient light for correct exposure or to obtain motion-free images can sometimes be difficult. Using a higher ISO is equivalent to using a more powerful flash, however this produces more image noise. On my current cameras, ISO 800-1600 generally produces 'acceptable' results.

Aperture - A wide aperture is desirable to isolate the subject from the background and to increase the maximum working range of the flash, however, I usually reduce the aperture by half an f-stop to minimise the affects of any auto-focus errors.

Shutter speed - The shutter speed should generally be set to the maximum flash sync-speed which for most cameras is around 1/200s. In darkness, fast shutter speed is irrelevant because it is the short duration of the flash output which freezes motion.

For stationary subjects, low shutter speeds can be useful for recording ambient light. The Barking owl below remained sharp because it was exposed by the pulse of light from the flash, whilst the background and twilight was revealed using a long 1/15 second exposure.

 

For flying birds such as the Nightjar below, low shutter speed 1/30s, combined with 'rear-curtain sync.' can be used to produce light trails, giving the illusion of speed. Often however, a potentially good image, such as the Grass owl with prey, shown in the second image below, is spoilt by excessive blur.

 

 

 

NOCTURNAL EYES

Pupils - A bright continuous light source produces contracted pupils when the bird is looking directly at it (or you). This is especially noticeable for a bird with a pale iris such as the young Boobook below. Large eyes are a prominent feature of nocturnal birds and if we could see in the dark we would notice their pupils are always wide open. I consider dilated pupils look natural and can be captured by pre-focusing the camera then turning off the focus light just before releasing the shutter (right-side image below). When focus is achieved and before the shutter is released, the subject can be observed through the viewfinder using a very dim 'moon-glow' light.

 

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 further away from the camera or moving closer to the subject, the likelihood  of red-eye can be significantly reduced. This is illustrated in the diagram and images of a Tasmanian Boobook owl below.


 

Red-eye correction -  Sometimes you cannot avoid red-eye as seen in the left and centre images above, however usually it can be 'fixed' with good photo-editing. Pupils almost always have some light and colour, so I try to  darken them by 'burning' the shadows and mid-tones, then desaturating the colour until they are almost black. You can also 'dodge' the catchlights and eye reflections to enhance their appearance, as shown below. In close proximity to an owl at night, a single light source often produces multiple catchlights due to reflections from the cornea and the internal structures of the eye.

 

 

FLYING BIRDS

A sharp image of birds flying at night is probably the ultimate challenge. A sharp image 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 the perch it was hunting from and watching it with dim light until it flew. The Grass owl was focused in flight using a high intensity focus light.