Photo 101: ISO


Your ISO, aperture and shutter speed settings all work together to determine how much light hits the sensor in your camera.  This blog post will focus on ISO but keep in mind that one affects the other.slides

Once you start getting a grasp on setting your camera manually you’ll come up with a system that works for you.  This is how I do it:
I typically begin by setting my ISO setting before aperture and shutter speed.  I take a look at my surroundings (see graphic below) and set it based on that.  For bright, outdoor photography you can set your camera on the lowest setting, around 100.  If you’re in a cloudy area you may want to set it closer to 400.  If you then are in the shade or the sun is starting to set you can crank it up to 800, 1000 or higher.  Indoor photography with no flash may require you to set your ISO at 2000 or 3200 so that your image is bright enough.  slides9

See the images below.  I kept all of the settings on my camera the same except the ISO so you can easily see how it affects your image.  iso photo 101 (1)

So you might ask, why not just keep the ISO high to get bright images?  I’m sure you’ve all seen photos taken at night when they begin to get “grainy” or “noisy.”  The higher you set your ISO the lower the quality of the photo.  So you want to try to keep the ISO setting as low as you can.  If you look at the images below you can see see the noise in the second image, especially in the background.  The third image is a close up so you can see it better.photo101_iso_noise-1photo101_iso_noise-2

Here are a couple of real life examples from photo shoots I’ve done.  This first session was out at the beach midday.  I don’t typically shoot at this time because the sun is so harsh but we had to work around schedules and some crazy weather.  It was really bright outside so I set my ISO to 200.  100 would have worked, too.stein-12

This photo, on the other hand, was taken inside a room with one or two windows to my right.  It was pretty dark so I set my ISO to 3200 to brighten the photo and it allowed me to set a shutter speed that was fast enough so any movement the dog made didn’t result in her being blurry.aiden-15

See my other blog posts about aperture and shutter speed to help you understand how they all work together:


Shutter Speed

How to Find Good Light

Tips & Tricks for Photographing Children

I live in Charleston, SC and offer one-on-one lessons!  Contact me at if you have questions or would like to customize a lesson for you!

Thank you Emily at Texture Design Co for creating my graphics!

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