Nobody seems to have problems taking great looking photographs in daylight or well-lit environments. Take your camera out in to the garden on a sunny afternoon and your shots will appear bright, pin-sharp and beautifully saturated, time after time.
However, once the environment becomes too dark, many beginners struggle to capture the scene correctly, resulting in blurred and underexposed shots. Commonly, this failure is treated with “It’s too dark to photograph”, or with the acceptance that a more expensive camera is needed – neither of which are strictly true.
F/5.6, 1/50s, 200mm, ISO 1600
One frustration for professional photographers is seeing someone resort to using their camera’s pop up flash to try and illuminate a scene with low ambient light. This will often result in unsightly shadows, harshly lit subjects and simply spoiling the overall lighting of the scene you’re trying to capture.
There are a couple of ways to overcome difficulties with low light photography. One is to buy a lens with a wider aperture (lower F number) to allow more light in to the camera. Something around F/1.2 to F/2.8 would make a huge difference here. However, lenses at this aperture tend to be expensive. Another option is to shoot at a wider aperture on your current lens. Shooting at F/4 compared to F/8, for example, will allow four times as much light in to the camera. The downside of increasing your aperture is, of course, a reduction to the depth of field – something you may not want for the shot you’re taking. Furthermore, if your camera has a filter attached, take this off. It will kill the amount of light coming through to the sensor.
But let’s address an often-overlooked solution to shooting in low light – ISO, and understand why it’s perhaps the most effective option.
F/1.8, 1/250s, 50mm, ISO 1600
Your camera’s ISO setting is a measure of its sensitivity to light. Many modern-day digital cameras, and all DSLRS for that matter, have the benefit of being able to switch between ISO levels at the press of a button – much more efficient than with film, where the need for a different ISO level means changing the entire roll of film.
Typically a digital camera’s ISO settings range in 100s – 100, 200, 400, 800 etc. Most will include much narrower increments too.
The higher the ISO, the more sensitive the camera’s sensor is to light. Doubling the ISO value essentially doubles the sensitivity – also known as ‘one stop’ of exposure. 100 to 200, 400 to 800, 3200 to 6400 are all one stop increments. Where you might need to increase the length of time your shutter is open by two stops, from say 1/500 second to 1/125 second in order to expose the scene correctly, you can now keep your shutter speed at 1/500 second and just increase the ISO by two stops instead (100 to 400, or 400 to 1600 for example). This is useful in situations where a slower shutter speed isn’t an option – at a concert or night-time sports event for example, where you need to keep the action sharp.
F/2.8, 1/500s, 200mm, ISO 3200
Using ISO to increase light sensitivity does come with a drawback, however – image noise. This adds grain to your images as your camera’s sensor tries to capture every speck of light, even from perfectly dark areas of the composition. But this can be easily rectified and reduced post-production by a host of editing software. Personally, I use Adobe Lightroom 4 as it enables the user to adjust the level of noise reduction together with other attributes such as colour and contrast noise detail. However, this is by no means the only tool available.
Don’t forget, if you’re shooting in low light, make sure you’re shooting in RAW format. This not only increases the level of detail you’re capturing, but also makes any post-production noise removal much more effective.
So remember, next time you’re in a low-light situation and your photos are coming out under-exposed or blurred, keep that flash turned off, open up the aperture slightly (lower F number) and get in to the frame of mind of ramping up your ISO. The setting is there because it works.
Author – Oliver Pohlmann