ISO is an integral part of the exposure triangle in photography, along with shutter speed and aperture. It allows you to control the light sensitivity of your camera’s image sensor, impacting the exposure and quality of your photos.
What is ISO?
ISO, an acronym for International Organization for Standardization, represents the sensitivity of your camera’s image sensor to light. A lower ISO number (like ISO 100 or 200) means less sensitivity, while a higher ISO number (like ISO 1600 or 3200) means more sensitivity.
How Does ISO Affect My Photos?
Exposure: Adjusting the ISO influences the brightness of your photos. If you increase the ISO (choose a higher number), your photo will be brighter. Conversely, if you decrease the ISO (choose a lower number), your photo will be darker. This can be handy when you’re shooting in conditions where adjusting the aperture or shutter speed is not enough or undesirable.
Image Noise/Grain: The downside of increasing your ISO is that it adds noise or grain to your photos, which can detract from image quality. Noise becomes more noticeable as you increase the ISO setting. At lower ISOs, your images will generally be clearer and sharper, with smoother tones and colors.
Choosing the Right ISO
The choice of ISO primarily depends on the lighting conditions and the desired outcome:
Bright Conditions: In well-lit situations, such as outdoor shooting on a sunny day, you can use a low ISO setting (e.g., ISO 100 or 200), as there’s already plenty of light available.
Low Light Conditions: In darker conditions, such as indoor environments or nighttime shooting, a higher ISO (e.g., ISO 800, 1600, or higher) may be necessary to get a properly exposed image. However, be cautious about noise in your photos.
Balancing ISO with Aperture and Shutter Speed: If you want a fast shutter speed to freeze motion, or a small aperture for a larger depth of field, and the light isn’t enough to achieve those settings, you may need to increase the ISO.
Learning how to control ISO is key to achieving well-exposed photos, especially in challenging light conditions. It’s a valuable tool, but needs to be used judiciously due to the risk of introducing noise. As with most elements of photography, mastering ISO comes with understanding its effect on your images and lots of practice.