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What is ISO?

ISO (or film speed), is used to determine the speed at which an image is captured, either on film or on a digital sensor. The ISO number determines the sensor's sensitivity to light. To change the ISO with film cameras, the whole roll of film had to be swapped out with a different roll. With digital cameras, it’s a simple setting that can be changed easily. Higher ISOs are more sensitive to light, but they are also much grainier and have more “noise” than lower ISO speeds. Here are some simple guidelines to help you know which ISO to use.

These guidelines are simply a starting place. Depending on your specific lighting scenario, your ISO may vary from what is suggested here. When you're out taking pictures, try this: Set your aperture to your desired setting, and then choose your ISO. If the shutter speed is too slow, adjust your ISO to a higher number until the shutter speed is fast enough.

Here are a few examples of when I have used ISO 200 and ISO 800.


Susy said...

I love this post. Thank you so much. I kinda understood ISO but I didn't know what ISO I needed for each setting. I'm so happy to have a guideline now.

Michelle said...

I can't believe that second pic is ISO 800 -it looks so crisp! I have so much to learn...