Taking pictures after dark requires the same key controls as you would use in daylight – but they may be pushed to their technical limits in some situations. Understanding these limits enables you to modify your shooting practices to produce interesting and technically competent photographs.
Festivals like Vivid Sydney provide plenty of opportunities to take interesting pictures after dark. A 1/3 second hand-held exposure at f/4.8 with a 75mm lens on a M4/3 camera at ISO 3200. Exposure compensation of -0.7EV was applied to overcome the effect of the very bright central area and retain a natural-looking rendition of the scene.
Shooting in low light levels requires you to make some important decisions about how to balance three vital controls: aperture, shutter speed and ISO. This balance pivots on shutter speed since it’s the function that determines whether your shot is sharp.
So the first parameter to lock down is shutter speed: how low can you hand-hold the camera without encountering camera shake. This factor should be tested for all camera bodies and lenses you plan to use
A hand-held 1/5-second exposure taken at ISO 640 with a 27mm focal length using a M4/3 camera with -0.7EV exposure compensation to allow sufficient darkening of the sky to replicate the actual conditions. Sensor-shift stabilisation in the camera body allowed the camera to be hand-held.
The Importance of Stabilisation
Photographers using modern digital cameras are likely to have access to stabilisation, either built into the camera body as a sensor-shift system or in the lenses they use. Sony and Olympus are the leaders in sensor-shift stabilisation, while most other manufacturers rely on stabilised lenses, in which a ‘floating’ element (or group of elements) is used to re-direct the path of the exposing light in response to camera movement detected by gyro sensors.
Both systems provide similar outcomes. Photographers can expect at least two f-stops of shutter speed advantage at longer focal lengths. This means a shot that would require a shutter speed of at least 1/100 second without stabilisation could be captured at 1/25 second.
Many manufacturers claim their systems can support three or even four f-stops of compensation, although that could depend upon the longest focal length covered. Longer lenses require more correction than lenses with angles of view equivalent to or wider than 24mm in 35mm format, which may not require stabilisation at all.
In most situations, the default stabilisation mode is the one to use. When following a moving subject, switch to the panning mode.
An exposure of 1/10 second at f/5 with ISO 1000 was used for this hand-held shot of a family group around a fire. The shot was taken with a M4/3 camera with built-in sensor-shift stabilisation using a 40mm focal length.
Capturing Enough Light
Having determined your shutter speed limitations, the next issue to address is how to let enough light into the camera to achieve a satisfactory exposure. This means looking at the lens aperture.
The wider the lens aperture, the more light can enter the camera at a given shutter speed. Consequently, fast lenses are the best choices for low-light shooting. But we can’t all afford a set of fast primes and such a set wouldn’t be particularly portable. So most photographers settle upon zoom lenses ““ which, in the main, aren’t particularly fast.
This is where the third factor, sensitivity, comes into play. Modern digital cameras have overcome many of the issues that faced photographers who recorded on film. Today’s cameras provide much higher sensitivity settings and retain colour accuracy at high ISO settings. But if you use the maximum ISO sensitivity the camera supports, expect a reduction in picture quality due to image noise.
Small-sensor digicams struggle with image noise at higher ISO settings (ISO 1600 in this candid available-light portrait). If the shot had been captured with a camera with larger sensor, little noise would have been visible at the same sensitivity.
There is a point at which increasing noise makes shots appear very granular, which reduces picture quality. That point varies with different sensor sizes and can be influenced by image processing. Cameras with sensors larger than 12.8 x 9.6 mm (‘1-inch type’) should be able to produce ‘usable’ images up to ISO 3200.
How you deal with exposures will affect the amount of gear you need, your shooting flexibility and the end result you obtain. The following tips provide some guidelines:
1. Travel light. Depending on where you are, carrying a conspicuous camera at night may not be safe. You’ll be less noticeable with a smaller camera and single lens. Consider using a fast wide-angle zoom or, if you need some ‘working room’, an all-in-one ‘convenience’ zoom lens. Avoid using flash. Be judicious about who and what you photograph. It can help to have a companion to deflect any ‘aggro’ you might encounter and validate your activities. Don’t take unnecessary risks.
If you want to photograph people in crowded areas like night markets, make sure your camera is small enough to be inconspicuous. Compact system cameras (CSCs) are ideal, particularly if, like the one used for this shot, they have touch screen controls.
2. Know your equipment. Know how to operate your camera in low light and with minimal fuss and ensure you have a good feel for how fast it can focus in different conditions. Be prepared to use manual over-ride if the AF system starts to hunt. Make use of Custom modes to pre-set exposure combinations so you can switch quickly between them.
3. Look for the lights. Seek out places with good lighting and wait for something to happen. Find an interesting light source, look for an engaging angle and watch how the light illuminates the scene and subjects that pass through it. While you’re waiting, decide whether to meter exposures on the light source (which will throw at least some of the rest of the subject into deep shadow) or evaluate the entire scene and hope for an even distribution of dark and light tones.
4. Know what you want. If you’re after action you’ll need a high ISO and fast aperture. If you want to create light trails you’ll need some way to steady the camera (look for a wall or something similar to rest the camera on while taking the shot).
5. Know your location. Check out your shooting location in the daylight before embarking on a night shoot. Find out where the interesting buildings, monuments and parks are and what potential shooting opportunities they offer. Look for places where people are likely to congregate and places where there is water (reflected lights can make great subjects for night photos). Seek out different viewpoints, including from tall buildings and in subways.
Well-lit cityscapes can provide easy opportunities to take interesting photographs that include lights, people and traffic. This 1/50 second exposure was shot at ISO 400 with a 28mm lens on the Samsung NX1, an APS-C CSC. © Yang Ji Eul.
6. Check the weather and know what to expect. City lights will look great on a cloudless night. Streets gain additional reflective surfaces after a shower of rain and snow can add reflective areas that boost ambient lighting and add an all-over glow. But make sure you protect your equipment if it’s going to rain or snow and delay going out in the middle of a thunderstorm. Above all, stay safe ““ and keep your gear safe too.
Overcast skies and rain will reduce ambient light levels. But they can also provide opportunities to photograph elusive animals that you wouldn’t see on a sunny day ““ like this platypus. Make sure you have adequate protection for yourself and your equipment
7. Breathe in and squeeze. Keep your finger on the shutter release and when you have the subject framed perfectly, breathe in and squeeze down on the shutter button. Don’t lift your finger until the shot is captured. This technique will steady both you and your equipment and minimise camera shake with slow shutter speeds.
8. Set the ISO limits. If you know the ISO settings at which your camera’s images become ‘unusable’ it’s easy enough to avoid them by setting the upper limit to the Auto ISO range. Most cameras provide this adjustment. You can then leave the ISO on Auto, over-riding it if necessary in the knowledge that you risk visible noise. The Auto setting will always be biased towards low ISO values, giving you the best chances of obtaining relatively noise-free shots.
‘Around the campfire’ shots are fun to have but challenging to take as they generally involve a wide brightness range. Taking the shot at dusk, when there is still light on the subjects, avoids the need to add extra lighting and doesn’t require people to sit still during the exposure.
‘Usable Images’ Defined
Deciding what makes an image usable requires you to determine the end use(s) for the picture. Will it be displayed on a screen ““ or printed? And, if printed, how large will the print be? What if you want to use the shot both ways?
For screen viewing, the highest output resolution currently supported is 3840 x 2160 pixels, which complies with the 4K video standard. This is roughly equivalent to an 8.3-megapixel image and most screens support pixel densities of less than 100 (typically 72 ppi).
Tablets and smart-phones may have higher pixel densities but their screen resolutions are less. So for screen-based viewing, images that look good at 3840 x 2160 pixels will fit the bill, regardless of their pixel densities.
Printing images tends to suppress the granularity of image noise because of the way inkjet printers lay down droplets of ink and the resolving power of viewers’ eyes. Modern printers use six or more different inks applied with varying droplet sizes and droplets overlap when hues are blended. This suppresses the appearance of discrete pixels and results in a more continuous tonal range.
Because the pixel density is also higher, when the image is printed at a resolution of 300 pixels/inch, an image that looks good on a screen at 3840 x 2160 pixels will withstand close inspection when printed at A4 size or slightly larger. Even larger prints should look good when viewed from further away.
Excerpt from Low Light Photography pocket guide