ISO is one of the three pillars of photography, along with aperture and shutter speed. All three of them work together to form your photograph. Learning how to use all three is guaranteed to get you off auto mode and into the real nitty gritty of photography.
What Is ISO In Photography?
ISO is how sensitive your camera is to the available light.
- The lower the ISO number, the least sensitive your camera is to light
- The higher the ISO number, the more sensitive it is to light.
Every camera has a base ISO, and it’s different between brands. Overall, most cameras or film will start somewhere around 100 to 200, generally 100 for Canon and 200 for Nikon. This lowest level is the base ISO of your camera and will provide you with the highest quality pictures, provided that you can set an appropriate shutter speed and aperture.
Some DSLR cameras come with an ‘Auto ISO’ setting where you can set the maximum ISO number you want it to go to, such as ISO 800.
What Does ISO Do?
ISO allows more light to hit your image sensor. This is how it works:
- The more light available, the faster you can take a picture. Although too much light will end up with a grainy photograph, as there is too much noise in the image.
- The higher your ISO, the faster you can take a picture. However, the quality will reduce disproportionately to ISO.
Each ISO number (such as ISO 200) will double the amount of light from the one before it. The ISO number also shortens how long it takes to take the photo. For example, ISO 100 takes 1 second, ISO 200 takes ½ a second, etc.
How Do I Use ISO?
Changing your ISO will often happen in low light situations. Start at the base ISO of your camera and move slowly up from there. Test it yourself each time until you find the appropriate settings for that current context.
You may also want to change your ISO number when taking photographs of movement – it will freeze action. Read your manual to learn what your base ISO is and how to adjust ISO on your camera, as they are all different. If your camera has the ‘Auto ISO’ setting above, that is perfect for low light situations as it will adjust the ISO for you. This is an excellent way to learn what ISO to use in what situations, at least when it comes to low light photographs.
There are many reasons to practice changing your ISO in a variety of situations. Getting to know your camera will get you off auto mode and into real photography. Getting into manual mode opens up an entire world of photography that most people never see. Go out and play with your camera’s ISO to learn how to use ISO correctly. The goal is the sharpest photo possible, with as little noise as possible.
Here are a few answers to the question “When should I set my ISO?”
– Is the subject well lit? If what you are taking a photograph of has plenty of light you can move your ISO setting down.
– How much grain do I want? You may want more grain in your photo as an artistic choice, if so boost up your ISO setting.
– Is your subject moving? With a moving subject in a dimmer area you may not be able to lengthen your shutter time, in which case you can try bumping up your ISO setting.
– Do you not want to use your flash? You might be somewhere that doesn’t allow flash, or using it may ruin the mood of the photo you are taking. If that is the case, up goes the ISO setting.
- ISO, aperture and shutter speed all work together to form an image.
- Look for an ‘Auto ISO’ feature on your camera when you are just starting out.
- Check the manual for your camera to learn how to adjust ISO.
- ISO allows more light into the image.
- Each ISO number doubles the amount of light hitting the image sensor.
- Each ISO number reduces by half the amount of time it takes to take the picture.
- The goal is the sharpest photograph possible, with as little noise as possible.
One trick I’d recommend out the most is to test by changing the ISO setting frequently and you will learn faster.