Using ISO with DSLR cameras is one of the most important skills that you will ever learn. It determines how sensitive to light the sensor will be, and it can change your exposure triangle drastically. This post will discuss what ISO means, how it affects your exposure triangle and creative ways that you can use the setting to get different photos.
What is ISO and how does it work?
Using ISO with DSLR cameras is integral to your mastery of the effect that light has on the quality of your images. The ISO measures how sensitive a camera is to light. The higher the number, the more sensitive it is, so less time with the camera open will be needed for a good photo. This also means that images will have more noise when there are high ISOs, but lower ISOs produce cleaner photos without so much noise.
ISO stands for International Organization for Standardization. ISO is measured in numbers and usually starts at 100 and ends at 12800. The higher the number, the more sensitive your camera is to light.
If you are using a camera inside with artificial lighting, start your ISO at 100 and adjust up or down depending on how bright it needs to
ISO History and Current Standards for Digital Cameras
ISO stands for “International Organization for Standardization.” It was created as an international standard in 1975. The original ISO standards were set at ASA (American Standards Association) speeds, which are now outdated. Newer DSLR cameras typically have an ISO range of 100-6400
How does ISO affect the exposure triangle?
ISO is like the film speed of a camera. If you are shooting with a DSLR at night and your aperture is f/11 or higher, it helps to change the ISO setting. If you do not, then it can be blurry from long exposures. By changing your ISO, you make it easier to take a photo without having the camera shake from being too close. The shutter opens faster and it isn't blurry.
Choosing the proper ISO for your available light
If you are shooting in a studio or with artificial lighting, lower ISOs should be used because it does not require as much light to expose the photograph properly. The general rule of thumb when photographing in controlled lighting is to start with your ISO at 100 and adjust accordingly depending on how bright you need it or if you are hand-holding the camera, using a tripod, etc.
For example, let's say that I'm photographing my child in our playroom which has a lot of natural light. In this situation, I would start by setting my ISO to 100 on my camera and adjust the aperture and shutter speed settings accordingly. If I needed more light because the room was too dark, I could either open up the aperture (making it a f/stop of less than 11) or increase the shutter speed. If I was photographing my child outside in natural light, I would start by setting my ISO to a higher number like 400 or 800 because the sun is providing more light than what is available inside.
Limitations caused by ISO
ISO affects both exposure and grain so as you increase your ISO to be able to shoot faster with less light, remember that there will be more noise in the image and therefore may require post-production editing such as noise reduction software. Also, when shooting at higher ISOs, your camera's lens will not be able to zoom as far. This is because the higher you go with ISO, it becomes more difficult for a DSLR camera to focus and therefore lenses can't always reach their maximum optical zoom capabilities when shooting at high ISOs.
The photos above demonstrate the impact of changing the ISO on the exposure triangle.
In the first image, the ISO is set to a minimum of 100 with a longer shutter speed. This allows more light to hit the sensor. At this point, the image will not have any appreciable noise.
In the second image, the ISO is lengthened to 1600. The shutter speed can now be reduced to 1/160 of a second. The image now has noise being introduced.
The third image is taken with an ISO of 6400 and a fast shutter speed of 1/400 of a second. It now has significant noise in the image.
When the ISO is changed then either the aperture or the shutter speed must be changed for correct exposure. This demonstrates how the exposure triangle functions. Keep in mind that different cameras have different limitations on how high or low they can set their ISOs.
What are some Creative Uses of ISO?
Besides being used as a guide to adjust the exposure triangle, there are other ways photographers creatively use ISO. In one example, a photographer will set his ISO as low as possible to produce the cleanest photo he can achieve. He will then use this image as a base and overlay it with another shot at a much higher ISO that captures motion or other special effects. This technique preserves detail from the lower quality image while also adding graininess from the high ISO image.
How do you set your camera's ISO setting?
ISO will be different on each camera. On the Nikon D7200, you need to hold the ISO button while rotating the command dial. On a Canon EOS T7, you will press the ISO button and use either buttons or the command dial to set it.
Important things to know about using high ISOs, such as sensor noise and color shifts
- Remember that the higher the ISO, the more noise you will get in your photos. This is something to keep in mind when deciding whether or not to use a high ISO setting.
- The “graininess” or smoothness of your photos can be greatly affected by the ISO you use. Try different settings to see what works best for your own style and creative goals.
- Be mindful that a high ISO will increase the noise in your photo.
- The color shift caused by using high ISOs can be corrected in post-processing if needed.
- ISO is just one aspect of the exposure triangle, so changing it will affect the other two elements (aperture and shutter speed) as well. Experiment with different ISO settings to see how they impact your photos and find what works best for you.
It’s time to get creative with ISO! Find out how it works, and what are the consequences of using different ISOs. Whether you want a blurry background or more vibrant colors, there is an ISO for that! Experiment with various settings on your camera until you find one that suits your style. Don't forget about sensor noise; too much digital noise can ruin even the best photograph (unless maybe it's intentional). So experiment and have fun with your photography.