**Special thank you to Oh Loops Yarn for sponsoring the yarn for these tutorials! These will be a supplement to a larger tutorial coming soon!**
In this tutorial and three others, we are going to explore the Exposure Triangle. The exposure triangle is the combination of three ways to help light enter your camera: Shutter speed, Aperture, and ISO. These three aspects of photography will help your camera get the correct exposure, while giving you complete control on how you want each final image to look. We will start with each piece of the triangle, then look at how those three pieces work together.
ISO – How Does It Work?
In the previous exposure triangle tutorials, we talked about how light enters a camera through a lens and lands on a sensor. This sensor is what captures the image to create a photograph. In this tutorial, we will talk about ISO. ISO is the rate the sensor will absorb light. ISO measurements are written in increments of 100, such as ISO 200, ISO 800, and ISO 2,000. Higher ISO numbers mean light is being absorbed onto the sensor at a faster rate, making the image brighter. Here is the same photograph shot with different ISO rates:
SO is an excellent tool to use when you need to increase the amount of light in an image without changing the aperture or shutter speed. However, raising ISO does come with a cost. Higher ISO will result in more noise in an image, which is the graininess and color distortions shown below.
While the DSLRs currently on the market advertise handling extremely high ISOs, keep in mind that these levels will result in a very high amount of noise in the image. Fortunately, today’s sensors on an entry level DSLR can handle ISO levels up to 1,000 and above without too much noise.
How Do I Adjust ISO?
ISO adjustment can only happen in the Manual (M), Aperture Priority (A or Av), Shutter Priority (S or Tv), or Program (P) modes on your camera. All of the other modes will automatically adjust the ISO level for you based on the level of light entering the camera.
There are a few ways to adjust ISO. The first is to manually set it in the menu system. While you should always consult your manual to see your exact model of camera, here is how I can manually set the ISO on my Nikon D5200.
I have found this way of setting ISO to be extremely tedious, especially when I am on a photoshoot that will have light changes. Instead, I have mapped the Function (Fn) button the side of my camera to adjust the ISO when I spin the adjustment dial. Here is how I do that:
You can also set the ISO to automatically be as low as possible while still exposing the image correctly. Here is how I do that on my camera:
**Thanks to the youtube channel Camera Guides for all of the helpful videos!
What ISO Do I Use?
The level of ISO you set will depend on the amount of light coming in to the camera. In bright sunlight, use lower ISOs to create the least amount of noise. In dark situations such as photographing street lights or night photography, use high ISOs to allow the light to be absorbed as quickly as possible. Be sure to download the exposure guide I have created for you to have an at-a-glance guide on how ISO levels will adjust the light and noise levels. Here are some images I have taken with explanations for each of the ISO levels:
When you have had an opportunity to play with your ISO levels, here are some extra tips I have for you in using ISO:
- I set my aperture where I would like it, then set my ISO to the lowest number possible while maintaining a shutter speed of at least 1/200. When doing portrait or product photography, this creates the least amount of noise while still having a high enough shutter speed to expose the image correctly.
- I use higher ISOs occasionally to overexpose my image if I want to photograph a subject in front of a bright window. I often already have the lowest aperture and shutter available in these types of images, so raising the ISO is a quick way to make the window appear completely bright and correctly expose the subject in front of it.
If you are interested in learning more about ISO and how it works, visit some of my favorite sites and read their take on it:
- Capture By Lucy: What Is ISO? Photography Tutorial #BACKTOBASICS
- Improve Photography: PHOTOGRAPHY BASICS #2: APERTURE, SHUTTER SPEED, AND ISO
- Expert Photography: Understand ISO in 4 Simple Steps