ISO Definition in Photography
There are many technical terms in photography, therefore, as a photographer you need to know if not all, but certainly most of them. Therefore, ISO definition is one of them.
The Exposure is the most important technique in photography, and can be controlled by Shutter Speed, Aperture and ISO. However, in this article I just cover the ISO Definition in Photography.
What is the ISO?
ISO in photography terms is a measurement unit which measures the sensitivity of our media (film or digital sensor) to light. In simplest terms the higher the number the more sensitive the media is to light.
We’ve seen that we can control the exposure through choices for Shutter Speed, Aperture and ISO. When it comes to low light situations, to maintain a certain shutter speed or to use a desired f-stop, we have to adjust the ISO.
Faster Shutter Speed, Higher ISO
As a rule of thumb, photographers prefer to use the lowest possible ISO to keep the sharpness and dynamic range in their photos, however there are times when you want to capture a moving subject (such as sport photography or taking photos of kids) and there is no other choice than to use a higher ISO setting. After all a noisy (grainy) photo is far better than a blurry one!
Low ISO vs High ISO
Generally speaking, you want to stay with lowest ISO setting when you shoot landscape, portrait and detailed images such as macro photography. However, for moving subjects you should consider a faster shutter speed, therefore you need to use higher ISO.
Can you give us an example?
As an example if your subject is a bird in flight and you want to keep everything sharp and you are using a 300mm lens at f5.6, your minimum shutter speed should be 1/500s or faster. With your shutter speed set to 1/500s and your aperture at f5.6, check your camera’s light meter for exposure.
If your camera cautions for under-exposure (usually there is some kind of warning that tells you the exposure is not correct), instead of reducing shutter speed (which results in a blurry photo) or opening up the f stop (which will give a shallow depth of field), increase the ISO till your camera’s built in meter stops asking for more light!
Finally, there are more to learn about the ISO and the Exposure, which I cover in our Digital Photography Bootcamp. Come and join the bootcamp to learn more about the Exposure.
That is all for now. Stay tuned for my next photography Tips. We love to hear from you. Let us know if you have any questions, feel free to send us your questions and we will be more than happy to answer them. Follow us on Facebook, Instagram and Twitter for more Free Tutorials and Tips.
Ted and the Omnilargess Team