A shot in the dark

ISO values can seem scary but don’t let them haunt you any longer! Dan Mold shows how to use ISOs to achieve sharp shots in low light

- Dan Mold

THE MISSION

Understand the role ISO values play in the exposure triangle and how they affect image quality

Time needed One hour

Skill level Intermediate

Kit needed • Kit lens • Tripod

There are three main parameters that make up your camera’s exposure: aperture is the diaphragm of blades inside the lens that open or close to let in more or less light, then you have how long the shutter is open for, shutter speed, and lastly, you have ISO values.

ISO stands for International Standards Organisation, the company that standardized values of light sensitivity for rolls of camera film back in the day. In modern digital cameras, ISO has a similar function, but you don’t have to switch rolls of film to achieve different ISO speeds as digital cameras allow you to do all of this at the press of a button.

ISO determines how sensitive your camera’s digital sensor is to light. A low ISO value, such as 100 (the baseline on many Canon EOS cameras) is a low sensitivity setting, so will take lots of light to create a good exposure, but it does provide the ‘cleanest’ images and best quality. You can however crank up the ISO value to a much higher value, say ISO25,600. This will make it much easier to achieve a good exposure in very low-light environments, but at the cost of introducing digital noise, reminiscent of film grain, and some softening details. Think of ISO alike the gain control on an amplifier, it will boost the signal, but distortion increases as a result.

In this project, we’ll go through everything you need to know about ISO, and noise reduction, so when you’re out shooting next, you know exactly which ISO setting to use.