What is ISO in Photography?
Are you on a journey of learning photography? If one of your goals is mastering the basics of exposure and shooting in manual mode, then this post is for you! Today I will be answering the question: What is ISO in photography? What is ISO on a camera? Keep reading and we can sort through this basic photography setting together!
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What is ISO on a camera?
ISO is one of the three components that make up the exposure triangle, along with aperture and shutter speed. In digital photography, ISO on a camera controls how sensitive the camera sensor is to light. When using a lower ISO such as 100 or 200, the camera sensor is less sensitive to light. Decreasing ISO will result in a less exposed image. When using a higher ISO such as 1600 or 3600 the camera sensor is more sensitive to light. Increasing the ISO setting will result in a more exposed image.
ISO Settings and Film Photography
Above is an explanation for ISO in digital photography, but what is ISO in photography with film cameras? In film photography ISO is dictated by the film stock you choose. It doesn’t matter what the ISO is set to in your camera, but ISO will remain the same based on the film you are using. Film ISO, also known as box speed, is indicated in the name. Kodak Portra 400 has an ISO or box speed of 400. Kodak Portra 800 has an ISO of box speed of 800. Just as with digital photography, film stocks with a box speed of 800 or 1600 are more sensitive to light than film stocks with an ISO or box speed of 200 or 400. As a result, when shooting film, the only settings you have to worry about choosing are aperture and shutter speed.
ISO and Grain
Each component of the exposure triangle (aperture, shutter speed, and ISO) dictate the exposure of an image. However they each also have a secondary function. Changing the ISO used to create an image also impacts the overall clarity of the photograph. Using a higher ISO results in increased grain or noise. Using a really high ISO such as 6400 or higher has the potential to degrade the overall image quality. This is especially true is the image is still underexposed despite using a high ISO. This secondary function also applies in film photography. Film stocks with lower ISOs are clearer and have less grain than film stocks with higher ISOs.
My Preferred ISO Settings
If you’ve read my previous posts about the exposure triangle, you may remember that as a portrait photographer, I prefer to choose my aperture first. I choose this based on the number of people I plan to photograph and the artistic feel I’m aiming to achieve. Secondly, I adjust my shutter speed based on whether I anticipate a lot of movement from my subjects. I keep it high enough to avoid camera shake. Thirdly, I adjust my ISO settings.
I personally prefer to keep my ISO at 800 or lower in order maintain clear image quality. Technically, my Sony a7IV can go up to a setting of ISO 204800. Wowza. However, I have found that typically, when going above ISO 800 more noise than I like starts to creep in. The effect becomes worse if I have under exposed the image and then try to increase the exposure in Lightroom.
Play around with your own camera and see what you like! You may find that you like a little noise or want to intentionally add some grain to your images. I certainly break this rule at times with photos of my family around the house. However, for client work I prefer to stick to lower ISOs for better image quality. I offer wall art to my clients and it has not been uncommon for my clients to order large prints.
Troubleshooting ISO in Photography
What if you’ve chosen your aperture and shutter speed, but a really high ISO is required for a properly exposed image? If I’m outdoors in natural light, I will first opt to lower my shutter speed. If lowering my shutter speed to the bottom of my acceptable range doesn’t fix the issue, then I may reconsider my aperture. For indoor work, if I’m unable to get a good exposure without a super high ISO, I always opt for adding flash as supplemental light.
How to Change Your ISO Setting
Every camera make and model is a little different. Generally, on digital cameras, there is an easy way to adjust the ISO setting on the camera body. Remember, in film photography, the ISO setting is dictated by your film stock. The only reason to change the setting on your film camera would be if you were using an in camera light meter.
On my Sony a7IV, there is a little control dial on the back of the camera body. On the right side of the wheel is printed “ISO”. If I click the wheel to the right, the ISO menu pops up on the screen and I can wheel clockwise and counterclockwise to adjust the ISO setting.
How to know what the ISO was on a camera after you’ve taken the photo
Have you ever taken an image and then weeks or months later thought, what settings did I use? What was the ISO on the camera when I used it? With digital cameras, there are several simple ways to find that info! If the image is still on the SD card, just put it in your camera. Push the “view” button and then the “display” button until that data appears! Once again, these specific steps/settings may vary depending on your camera. However, most digital cameras make this information easily accessible. With film photography, the ISO will be dictated by what film stock you used.
If the digital image lives on your hard drive or computer, you can still locate this info! On a mac, right click the image file. Then select “get info”. Under the “more info” tab you can view several of the setting used including your ISO setting.
What questions do you still have about “what is ISO in photography?”
Do you feel like you have a more solid understanding of “what is ISO on a camera?” I hope this post has helped you take one more step towards mastering the art of photography. If you have questions, feel free to contact me via email or sign up for my email list below!