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 and my techniques and equipment have progressively evolved. The additional equipment required for wildlife can be as simple as a decent camera with good focus-light and an assistant. When working from a car or with an assistant, photography in the dark is fairly straightforward. When alone, adjusting camera and flash settings is error prone and I find it beneficial to pre-configure as many settings as possible before nightfall.

 

ILLUMINATION

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

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 photography in natural light, this can be ignored because the relative distance from the light source only changes by an infintesimal amount. When illuminated with artificial light this is not true, as the diagram below illustrates. If the distance is doubled, the exposure needs to be four times longer or two f-stops wider. If the distance is halved, the exposure needs to be reduced by the equivalent of two f-stops.

 

 

Continuous light sources such as spotlights are great for photographing stationary or slow moving animals. Filament lamps and Xenon arc lamps produce light having excellent colour quality but are heavy and power hungry. LED lights are portable, bright and energy efficient and those having a high colour rendering Index (CRI greater >80) produce excellent photographic colour rendition.

Exposure is determined with camera metering system by adjusting shutter speed, aperture and ISO. The Tawny Frogmouth below, was illuminated using the car high beam, with camera settings of 1/15s, f5.3 and 9,000 ISO. The disadvantage of continuous light sources is very low intensity compared to electronic flash.

 

 

Electronic flash is the ideal portable light source because it emits a super intense burst of high colour quality light which can freeze rapid motion, however an additional light is required to enable the camera to autofocus in darkness. Flash units contain complex electronics that produce an electrical discharge inside a transparent tube and when sufficient light has been emitted, the discharge is terminated. Most models have auto and manual modes which can be configured to produce the correct exposure An electronic flash on full power is equivalent to using a shutter speed of approximately 1/250s and on 1/4 power is equivalent of 1/4000s shutter speed.

Advanced electronic flash units have several automatic and manual exposure modes. Properly exposed images can be obtained using manual power settings if the subject distance is known, however,  'TTL mode' (through-the-lens) can produce well exposed images at widely varying subject distances regardless of the background brightness. For this reason, TTL combined with front-curtain sync has become my preferred  mode. The advantage of TTL is illustrated in the series of full-frame images below, taken at widely varying subject distances with the flash exposure compensation set to -1.

 

In TTL mode a pre-flash is fired just before the camera shutter opens, which allows the camera to calculate the 'correct' amount of power needed for the exposure. In rear curtain sync the pre-flash can be seen but with front-curtain sync, the pre-flash is invisible. Flash exposure compensation is usually required for optimum exposures. At the commencement of an outing, I 'calibrate' my setup by taking a couple of test shots of an object such as a tree trunk, to check alignment of the flash head and the required flash exposure compensation. TTL mode in 'front-curtain' sync is illustrated below. The interval between the pre-flash and the main flash is of the order of 50 milliseconds. 


 

 

FOCUSING

Autofocus sensors in DSLR and mirrorless cameras essentially adjust the focus distance to achieve maximum contrast on the image sensor. Illumination intensity, subject contrast, motion, and the particular camera/lens combination effect the ability of a camera to focus quickly and accurately. Mirrorless cameras unlike DSLR's do not always focus at the maximum aperture of the lens and I believe for night flight images, flagship mirrorless cameras such as the Nikon Z9, are not on par with high-end DSLR's.

A small flashlight can provide sufficient light to auto-focus (AF) on stationary subjects, however flying birds require much higher intensity light for rapid AF. The human eye is a poor judge of brightness and at night what may appear bright to the photographer  is often insufficient for fast autofocus on a moving subject. For flying birds, instantaneous AF requires an intense light source.

Nocturnal birds have poor sensitivity to red light, which I believe is the ideal colour for a focus light. Unfortunately intense red light usually degrades the final image and cannot be entirely eliminated from the final image by processing. To address this, I have developed an electronic circuit which turns the focus light off the instant that the pre-flash fires, so that none of the focus light appears in the final image. If you are interested, please see my articles (to be added soon).

 

GEAR

Cameras, lenses and flashes - A summary of the gear I have used for wildlife night photography is shown below.

1974-2004 (35mm film days with manual focus gear) Nikon F2/Nikon FM2 with Nikkor 300mm f4.5 manual focus lens and a Sunpack Auto 455 electronic flash

2004-2010 Nikon D70 (6 Megapixels) with Nikkor 70-300 f4.5-5.6 AF lens and Nikon SB-800 flash. My first DSLR and autofocus camera was a major improvement on manual focus and film

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

2012-2015 Nikon D7000 (16 megapixels) with Nikkor 70-300 VR AFS & 80-400 AFS VR lenses amd Nikon SB-800 flash. Better autofocus enabled photography of birds flying at night

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

2022 Nikon Z6ii (24 megapixels) & Nikon D850 (45 megapixels)  with 300mm f4 PF & 500mm f5.6 PF lenses and Nikon SB-800 flash - Better image quality than the D750 and the electronic viewfinder of the Z6ii is a joy because it can be configured to see clearly in almost total darkness. I use the D850 with 300mm f4 lens for flying birds.

 

Flash extenders - consist of a Fresnel lens placed in front of the flash, which concentrates the light output over a small area. They produce a 'hotspot' with a 3-4 f-stop gain in brightness and are useful for night photography with a telephoto lens. The images below were taken with a 50mm lens using identical exposure and processing, with and without a flash extender.

 

Flash brackets can be used  to minimise 'Red-eye' and aid focusing at night. I use a DIY carbon fibre bracket incorporating a LED spotlight for focusing
 

Tripods are useful for night photography at fixed locations such as perches, roosts or nests. A small lightweight tripod can support the camera or be used as a stand for an off-camera flash.

 

Off-camera flash - Occasionally, I use sync. cables or 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 foliage and other obstacles.

 

CAMERA SETTINGS

Settings Banks - Many cameras allow you to save your favourite settings for quick recall, which is a useful feature in the darkness of night.

 Image file format - RAW files have high dynamic range and the capacity for salvaging images which have been over or under exposed or taken with incorrect white balance.

 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 when possible check the image histogram.

 Shooting Mode - I always set the 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'. For stationary subjects,  backbutton focus makes it easy to reframe the subject without having to refocus. For flying birds, I use continuous autofocus and multiple focus points. Different camera brands and models have many different autofocus modes so you need to experiment to find which works.

 ISO - Producing sufficient light for correct exposure or to obtain motion-free images can be difficult. Using higher ISO which is equivalent to using a more powerful flash can help, however the downside is that image noise increases. ISO 800 produces 'acceptable' noise on my current cameras and is my preferred setting.

 Aperture - A wide aperture is desirable to isolate the subject from the background and increase the maximum working range of the flash. I usually stop my lens down slightly from maximum aperture because accurate focus is easier to achieve and lenses generally perform better when stopped down. Unlike DSLR's, mirrorless cameras may not focus at the maximum aperture of the lens which I believe makes AF worse than DSLR's at night.

 Shutter speed - The maximum shutter speed should generally be set to the maximum flash sync speed of the camera which is approximately 1/200s. At night where the surrounds are dark, a fast shutter speed is irrelevant because it is the short duration of the flash which freezes motion.

For stationary subjects, a low shutter speed can be useful  to record ambient light or to give the illusion of speed of a flying bird. The Barking owl below remained sharp because it was exposed by the short pulse of light from the flash, whilst the background is lit by ambient light but shows blur from camera movement associated with the 1/15s hand-held exposure.

 

 Flash combined with low shutter speed and 'rear-curtain sync.' can be used to give the illusion of speed. For the Nightjar below, a sharp image with light  trails provides the illusion of speed. A 1/30s exposure where the bird was illuminated by the focus light, produced the light trails an the short flash pulse produced a sharp image of the bird. This technique is a gamble because potentially good images, such as the Grass owl with prey below, can be ruined by the excessive blur caused by the 1/15s shutter speed and focus light. For  image of a Grass owl flying away, a faster1/200s shutter speed prevented the light trails the image appears looks much sharper.

 

 

 

 

 

NOCTURNAL EYES

Pupils - A continuous light source 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 the focus light off before releasing the shutter, as shown for the image on the right. Electronic viewfinders in mirrorless cameras can see in almost complete darkness and after focus is achieved, the subject can be observed with extremely dim light ( 'moon-glow' intensity) before  the shutter is activated.

 

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

Sharp images of a bird flying at night 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 with a dim red light until it flew. The Grass owl was focused in flight using a camera bracket similar to the one shown above.

 

CONCLUSION

My thoughts and methods are constantly changing and should be considered as a guide to the techniques that have worked for me (updated 2022-06-28)