Photography technology can sometimes be ridden with jargons that can be hard to decipher. The camera ISO setting is one of the three factors of exposure. It deals with the shutter speed and aperture.
The term ISO means International Organisation of Standardisation. It is the governing body that standardises sensitivity ratings for camera sensors and some other things.
The term was imported into photography from film. The ISO rating is also known as “film speed” and “ASA.” The standard means that there will be an equal rate of sensitivity across different cameras.
The ISO means the same thing on both digital and analogue cameras. It is the light sensitivity of the imaging sensor or film.
Changing the ISO on a digital camera makes the sensors more or less sensitive to light. The biggest feature on digital cameras is the ability to change ISO on the camera.
In the past when film cameras were used, people were stuck with the same ISO until the roll ran out.
Digital cameras have ISO settings between low sensitivity of 100 and a higher sensitivity of 12,800. However, compact cameras and phone cameras sometimes go below 100. Also, some interchangeable lens cameras go higher with hundreds and thousands of ISO levels.
The ISO value corresponds to exposure stops. For example, the ISO 6,400 is six stops above ISO 100. If an ISO increases from 100 to 400, the camera needs a two-stop decrease balance to maintain the same overall exposure value.
The ISO also affects the image’s quality. A higher ISO means a grainy or noisy image. The less the ISO, the lesser the noise in the image.
The lower ISO image will also have better colour and dynamic range. It means the camera will be able to capture details in shadows and highlights. This would mean that to get better quality images, the ISO needs to be as low as possible.
However, it will sometimes be impossible to get adequate exposure without increasing the ISO. For instance, images taken in low light or indoors will require increasing the ISO.
You may also need to increase the ISO when trying to capture an action image that requires a fast shutter speed.
ISO can be raised quite high on cameras with larger sensors without it affecting the quality of the picture taken. A DSLR camera or mirrorless camera will not be as affected with a high ISO, especially if you need to increase it to get the best shutter speed and aperture quality.
All these mean that even when a high-ISO image looks great on the camera or phone, it will most likely look noisy or grainy when printed out or viewed on a bigger screen.
Smartphones’ camera default settings also tend to apply noise reduction on JPEG images with high ISO. It does this by applying some blur to the image which can hamper on the details.
Photo editing software sometimes does the same things cameras do to slightly reduce the noise by blurring the image in some places once selected.
Meanwhile, it is advisable to apply noise reduction in post-production than as a setting on the camera before taking a picture.
At the end of the day, the ISO lets users take photos in faster shutter speeds, smaller apertures or in darker conditions.
However, this will result in a noisy image. This will explain why a lot of photos taken in the dark might appear grainy, lacking details.