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Camera ISO 101
Alongside shutter speed and aperture, ISO comprises the 3rd side of the “exposure triangle” making it a fundamental setting to nail to expose an image properly. Most people over complicate this setting but I’m going to explain why it’s actually quite simple.
What is ISO?
-It’s a numerical value that represents “light sensitivity”
In film photography the film itself is rated with a certain “ISO” meaning that film is more or less sensitive to light depending on the rating.
-Higher ISO is more sensitive
-Lower ISO is less sensitive
In practice you would buy film, let’s say 100 ISO film, the least sensitive to light. Then you’d adjust your shutter speed and aperture to obtain the desired exposure for the image.
You are constantly playing a game between those three settings to achieve proper exposure.
In digital photography we don’t use actual film so what is ISO now?
- It’s “digital gain” on an image.
- Said another way, it’s “artificial light sensitivity”
A digital camera is going to start off with a 100 ISO setting. You can then raise the ISO to to adjust exposure.
