Top Tips For Night Photography
Digital cameras have made low- light photography very much easier, but once night falls, many traditional techniques still apply… and there’s also an exciting new world of long exposures to explore.
Image stabilisation systems are becoming ever more effective, but there’s always going to be a limit on the slowest shutter speed for which you can hand-hold the camera and still obtain a sharp image. Once exposure times lengthen beyond about ¼ second, the camera will need to be mounted on a tripod… and the sturdier the better. Lightweight tripods may well be easier to carry around, but they can flex and create vibrations which will be problematic when making long exposures. Make sure the tripod is securely set-up and locked off… even the tiniest of movements will create blur and soften detailing. Use the foot spikes for a more solid location on soft ground; some photographers will also suspend a sandbag from the centre column for added dampening.
Once the camera is on the tripod, adjust the tripod head’s position as desired, but use the tripod’s tilt/pan controls… don’t try to move the camera for this, as it will loosen the attachment, potentially causing the camera to move slightly during an exposure. Tripod heads with quick-release plates are a good option if you’re planning to do a lot of night photography. Once the camera (or lens) is securely fitted to the plate (tighten the mounting bolt as much as you can), it can then be very quickly and easily fitted to the tripod – and then detached – without working loose.
➜ Exposure Bracketing
If in doubt, bracket your exposures. Now that you don’t have to pay for every frame (as was the case with film), bracketing exposures is a very effective method of finding the right one… simply establish the shutter speed you think
➜ Manual Exposure Control
You can shoot in many low light situations with the automatic exposure modes and the results will be excellent, especially when using multi-zone metering measurements. However, for night work it’s often better to switch to manual exposure control, especially when using long exposure times. This will allow you to make any adjustments that automatic exposure control would simply override. Most cameras have a maximum timed exposure duration of either 30 or 60 seconds, so anything longer will require the ‘B’ (bulb) setting, which can allow for exposures of up to 60 minutes or perhaps even longer. With the shutter set to ‘B’, you can time the exposure manually, as it will remain open for as long as the shutter button is kept depressed. If you want to avoid any problems with vibrations when shooting on ‘B’, perhaps think about investing in a remote trigger so you aren’t physically in contact with the camera during the long exposure.
Use a mid-range aperture such as f8.0 or f11 and then determine the shutter speed accordingly. If you always use the lens’s maximum aperture – which is often tempting when shooting at night – you’ll end up with a shallower depth-of-field, especially when using a longer focal length. will be about right and then experiment with both slower and faster settings. Remember that doubling a 15 second exposure, for example, will result in an exposure duration of 30 seconds, and another stop of exposure will lengthen this to 60 seconds which means, depending on your camera, you may have to resort the ‘B’ setting and manually timed exposure durations. When exposure times start to extend beyond 20 to 30 seconds, small adjustments in timing actually won’t make much difference.
If you want to avoid overly long exposure times you can adjust the apertures for bracketing, but remember that this will also have an effect on the depth-of-field.
➜ Colour Temperature
Although we perceive light as being essentially white, it actually rarely is, and usually contains a predominance of one colour described as a ‘cast’. Our eyes tend to automatically correct for a colour cast, but digital imaging sensors (and colour film) tell it as it is, which is important to consider when shooting under artificial lighting and at night. Artificial lights create different colour casts because they have a different colour temperature to daylight. Domestic tungsten lamps create an orange colour and fluorescent
tubes give a greenish cast. Obviously coloured lights will also create interesting effects.
The colour of light is expressed as a colour temperature value in degrees Kelvin – with the range encountered in photography being from around 3000 degrees Kelvin (very warm/ orange looking) to 10,000 degrees Kelvin (very cold/blue looking). Pure ‘white’ light is generally accepted to have a colour temperature of 5500 to 5600 degrees Kelvin.
A digital camera is able to adjust the colour balance during image processing so it can correct for the colour casts in both natural and artificial light. The white balance control (so called because its job is to achieve white whites) typically has an auto mode and a number of presets designed to cope with different types of illumination. While the auto white balance (AWB) is convenient it will also remove any colour cast that you might actually want, although some cameras now offer a ‘Keep Warmer Tones’ option. If you want to retain a prevailing colour cast, use the sunlight/ daylight preset which is balanced for around 5500 degrees Kelvin and so will ensure warmer, cooler or other tones are captured.
A neat little trick is that you can use some of these white balance presets as builtin warming/cooling filters – for example, understanding that the cloudy WB preset corrects for blueness by adding red. If you then use it when shooting a sunset, it will actually boost the orange/red colouring.
➜ Spot Metering
Modern multi-zone metering systems can be very reliable, but they work by evening out all the light and dark areas in a scene, which is something you may not want when shooting at night… especially in terms of preserving the mood or atmosphere of a more contrasty lighting situation. Alternatively, use the spot metering – or selective/partial area metering – and take a light reading off a mid-tone, then manually set the indicated shutter speed for the desired aperture setting (i.e. depending on how much depth-of-field you want).
In contrasty situations avoid the meter being overly influenced by large areas of brightness or deep shadow, particularly when using the multi-zone metering. If you want deeper shadows, you’ll have to deliberately underexpose. Alternatively, if you want brighter highlights, you’ll have to deliberately overexpose.
➜ Playing With Light
There are lots of ways to experiment with long exposures and night photography… try ‘painting with light’ using a powerful torch to ‘paint’ light on to objects such as trees or street furniture. Place a coloured filter over the torch to create different effects. However, you will need very long exposure times so the torch light registers on the film (experiment at two minutes, five minutes and ten minutes, and close the lens right down to f16 or f22). This technique is best tried in a location where there is very little or no available light (i.e. no street lights, etc.).
Another interesting trick is to mix flash with long exposures. Set the camera on ‘B’ and cover the lens with the lens cap. Position somebody in the frame, trip the shutter and fire the flash. Put the lens cap back on, move your subject and repeat the process. Do this as many times as you like, but remember not to double up the subject’s positions in the frame. You could make them jump up and down, start from a crawling position and gradually become upright… the sky is the limit. Once you’re finished, close the shutter… the flash-lit subject will appear many times on the single frame. Once again, this technique is best tried in a very dark location. Determine the flash output based on the subject’s distance and the aperture you select (best between f5.6 and f11). You can also experiment with the subject waving a torch or sparkler.
➜ The ‘500 Rule’
It’s night time right? So you’re going to need a long exposure, aren’t you? Well, actually not all the time. It’s a mistake that beginners in astrophotography often make, based on the assumption that stars aren’t really very bright so night sky exposures need to be long. What’s forgotten here is that the earth is spinning so the night sky is always moving, and it doesn’t take very long at all for pinpoints of light to turn into streaks or trails. If you want stars to be rendered as points – particularly important if you’re photographing features such as The Milky Way – then the exposure times actually need to be pretty short.
The ‘500 Rule’ is based on the lens focal length that you’re using (and hence sensor size also comes into effect). So, for example, if it’s 24mm, you divide 500 by 24 which is 20.8. So the recommended exposure time is 20.8 seconds with a full-35mm format sensor. If you’re using an ‘APS-C’ format camera, subsequently divide this number by the crop factor (i.e. 1.5x for Nikon, Fujifilm and Sony; 1.6x for Canon). The ‘500 Rule’ will ensure stars are still reproduced as points of light even with quite big enlargements. You’ll need to set a high ISO – try 3200 to start with – and an aperture of f2.8 or wider if available. Exposure times will obviously become progressively shorter as the lens focal length increase, but given most photography of the night sky is with wide-angle lenses, you’ll end
up with an exposure time somewhere in the range of ten to 35 seconds.
There is also a ‘400 Rule’ which means there’s an even greater guarantee of avoiding any streaking, but you’ll need a higher ISO setting, and noise levels could then become more of an issue.
As exposure times increase and the shutter stays open for longer, any movement in the scene will record as blurring. The longer the exposure, the longer the blur lines will become (a moving car’s headlamps or tail lights, for example) or the more pronounced the blurring effect (such as wind-blown clouds or tree branches).
There’s lots of scope for creative experimentation here, both with different types of moving subjects and varying exposure times. For example, if you’re shooting in an urban location where a lot of people are continually moving around (a town square maybe), with a long enough exposure you can actually make
There are various logistics to consider when shooting at night, including dealing with very them ‘disappear’… as they simply won’t be at any one spot long enough to be recorded.
Digital cameras suffer from increased noise with longer exposures, yielding grainy pictures. The same thing happens when selecting higher sensitivity (ISO) settings, as the output from the sensor is essentially amplified (which increases both the signal and the noise components of the signal-to-noise ratio). In-camera noise reduction processing for both high ISOs and longer exposures steadily continues to become more effective so that sharpness and colour saturation are less compromised, but there are other techniques available too, such as taking multiple exposures which are subsequently stacked postcamera. Using multiple exposures to create a cold temperatures, remembering that these don’t just happen during winter either. Clear nights are often quite cold even in summer, particularly in mountainous regions or deserts.
As you’re likely to be on location for many hours, it’s important to dress warmly, including a hat and suitable walking shoes. Fingerless gloves work well too, keeping your hands warm, but still allowing you to easily operate your equipment. You’ll obviously need a torch, but if you’re trekking to a remoter location, single finished image reduces the exposure time needed for each frame and allows for a lower ISO setting, so reducing the noise as well.
In-camera noise reduction for long exposures essentially performs dark frame subtraction, capturing a second ‘black frame’, which will help detect the ‘hot pixel noise’ (essentially of the sensor’s increasing temperature with longer exposures) so it can be removed. It’s effective, but total exposure times will obviously be doubled which means extra-long waits if you’ve been shooting at 30 seconds or even longer.
Various post-camera options are available for noise reduction and, of course, are the only choice you have if you’re shooting RAW files to optimise resolution. it’s a good idea to first do a recce in daylight so you’re aware of any potential difficulties along the way and have a better idea of where you’re going.
General safety rules also apply — particularly if you’re heading for a remote location. Make sure somebody knows of your plans and will raise the alarm if you don’t return as scheduled. Don’t take it for granted that you’ll have mobile phone service (which is something you can check beforehand if you do a recce).