The first part of understanding ISO is understanding what it stands for International Standards Organization, the governing body that standardizes sensitivity ratings for camera sensors. More importantly, what is ISO? ISO is a rating ranging in value from 25 to 3200, indicating light sensitivity. The range can vary from camera to camera. Though more advanced cameras can go as low as 25, most cameras will start at 100. Each value of the rating represents a stop of light and each increment, up or down, represents a doubling or halving of the sensor’s sensitivity to light.
The lower the ISO rating, the less sensitive the sensor is to light, making the image smoother with less digital noise. What exactly is digital noise? It is any light signal that does not originate from the subject, creating random colour in an image and giving it a grainy appearance. A higher ISO rating indicates a higher sensitivity to light, meaning the sensor has to work harder to establish an effective image and as a result produces more digital noise. A high ISO of 1,600 will produce a brighter picture than a lower ISO of 100 but it will also produce more noise.
Have you ever taken a photo at night with your cell phone or a point-and-shoot camera and noticed the photo looked grainy? This happens because the camera is compensating for the lack of light by selecting a high ISO. Fortunately, camera technology is constantly improving and newer cameras have a greater ability to use a high ISO with far less noise.
Sunset at ISO 100
Sunset at ISO 3200
Typically, you always want to use a low ISO, 100 or 200 when possible. As with aperture and shutter speed, ISO can also be used for stylistic effect. For instance, if you want to give your photo a vintage aesthetic just up the ISO a few notches. This is a great way to add this effect without any post process editing.
The ISO rating along with the shutter speed and aperture setting are the three elements that determine the final exposure of a photo. A hint of what’s to come. Happy Shooting!
Tags: PHOTOGRAPHY 101