In part two of learning your camera’s settings we’re going to explore your ISO settings. (If you missed part one, ‘Understanding Aperture Settings’ you can find it here. Like aperture and shutter speed, ISO is one of the three pillars of the ‘exposure triangle’. So far, we’ve learned that aperture affects exposure by adjusting the opening in the lens. Your Camera’s ISO settings affects exposure by adjusting the light sensitivity of the camera’s digital sensor. By adjusting sensitivity of the sensor, ISO determines how exposed or how bright an image becomes.
Before we get in to the technical details we need to define ISO. The acronym ISO stands for International Standards Organization. ISO represents the industry standard for the sensitivity of emulsion-based film. ISO film ranges from 100 to 1600, with 100 ISO being the least light sensitive and 1600 ISO being very light sensitive. In film photography, lower ISO film such as 100 or 200 should be used for normal daylight photography. More sensitive film with higher ISO numbers should be used in low light settings.
ISO for Digital Cameras
In digital cameras, ISO sensitivity is the measure of the digital sensor’s ability to capture available light. Digital cameras convert light exposed to the image sensor into an electrical signal for processing. ISO sensitivity adjusts by amplifying the signal. Your digital camera’s ISO range will generally start at 100, then double to 200, 400, 600… until it reaches the top of your camera’s range.
In basic terms, ISO settings will brighten or darken a photo. Each ISO increase will double the amount of exposure and brightness of your photo. If you’re using your camera in full auto mode, your camera will choose the best ISO settings for the lighting conditions. By putting your camera in manual mode you’ll be able to control the exposure level of your image yourself. The best way to show ISO setting differences is through photos.
ISO and Image Quality
Because it brightens your picture, higher ISO settings are great for low light conditions. The trade off for higher ISO light sensitivity is noise. Digital noise is tiny dots or specks of color in the image that are generated when the image sensors’ sensitivity is amplified to read more light . A photo taken at too high an ISO setting will show digital noise that will give your image a spotty, grainy look. The higher the ISO setting, the more noise you may introduce.
Base ISO Settings
Your digital camera comes with a base ISO setting which is your camera’s lowest ISO setting. Most digital cameras have a base setting of 100. Omit picture quality, it’s best to try to stick to your base ISO, or the lowest ISO setting possible for the lighting conditions. Unfortunately, there’s no set rule to where on the ISO spectrum image quality begins to drop. It depends on the individual camera and how the digital sensor handles noise. Generally speaking, more high-end cameras will produce less noise at higher ISO settings.
ISO User Tips
For ISO settings, you only need to remember a few things. A higher ISO number requires less light to get a properly exposed image. Too high of an ISO setting will give you a noisy, grainy image. It’s always a trade-off between better exposure and image quality. Use the lowest ISO setting possible to get the best possible image quality.