Understanding ISO

ISO is short for International Organisation Standard and is used to control your camera sensor’s sensitivity to light. The term was actually carried over from film, when the ISO rating was known as the ‘film speed’ and you were essentially stuck with whatever film speed you loaded into your camera, at least until you finished that particular roll. ISO 100 was the baseline speed, ISO 50 was also very popular.

Now on DSLRs, you’re able to change the ISO whenever you so wish, ranging from 100 to 12,800 or greater. Low values give the least sensitivity and high values give you the most. In brighter conditions, there is a lot of light and the sensor doesn’t need to be as sensitive. When light levels drop, the sensor needs to increase its sensitivity, therefore you increase the ISO.

Ideally the lower it is set, the better, as this will avoid visible noise and grain. You want to find a balance between how dark it is and how much noise you can get away with in your photos without it ruining the shots.

With a high ISO, be sure to have a tripod available to help minimise the movement involved that would possibly make it grainier. Although grain can be fixed to some extent with noise reduction in post production, it is a good idea to get it right during the shoot. An ISO of 100/200 is ideal as a lower ISO won’t just make less noise, but it will produce a better colour and dynamic range, which is the ability of the camera to capture detail in both highlights and shadows.

There is an option to set a maximum ISO value so the camera knows not to exceed that point, however, the downside is that your camera will start using progressively longer shutter speeds if it reaches these ISO limits, leading to more motion blur. Everything is a trade off.

If your subject is moving and you’re trying to freeze the motion, a higher ISO will allow for a higher shutter speed. If you plan to only show a small version of your image, such as on social media, you can get away with a high ISO.

Subjectively, the noise characteristics of a high ISO can lend a vintage look to your photos, although this is an effect that is often better left for post-processing

50-200

For very bright sunny days, creating the ultimate smooth and sharp image.

400

Good all-round setting suitable for overcast skies

800

Interiors, low light outdoor subjects or action photography

1600

Night shooting or indoor low available light, or with long heavy lenses - turn on noise reduction setting

3200+

Only push this high it needs be, will need noise reduction post shoot to sharpen and smooth image