ISO Definition in Photography Explained

What is the ISO Definition in Photography?

After digging a little, I found the following as per Wikipedia:

“The ASA and DIN film speed standards have been combined into the ISO standards since 1974. The current International Standard for measuring the speed of colour negative film is ISO 5800:2001 (first published in 1979, revised in November 1987) from the International Organization for Standardization (ISO). Related standards ISO 6:1993 (first published in 1974) and ISO 2240:2003 (first published in July 1982, revised in September 1994 and corrected in October 2003) define scales for speeds of black-and-white negative film and colour reversal film, respectively.”

The Basics of ISO

In basic terms ISO is the level of sensitivity to light in your camera. The lower the ISO, the less sensitive it is to light. A higher ISO increases the light sensitivity of your camera.

So what does it mean to have more or less light sensitivity?

With increased sensitivity your camera can capture images in lower light without using a flash and that’s a good thing right? Well, there is a drawback.

Your photos will have more grain or noise when you raise the ISO. Here’s an example of the same photo with low ISO and a high ISO.

You can clearly see the extra noise with the higher ISO.

Now that we know what ISO is, which setting should you use?

For the best image quality use the base ISO. In other words, the lowest ISO your camera can go.

Usually that’s either 100 or 200 depending on your camera.

What about when that’s not possible?

Setting ISO Indoors

Let’s say you’re indoors without natural light coming in. Well that would be a great time to raise the ISO.

Each time we raise the ISO it effectively doubles the amount of light sensitivity in the camera. This is why your ISO settings are in increments of 100 200 400 800 and so on.

Just remember the higher the ISO the more potential noise will be in your photo.

So, how do you know what to set your ISO at?

Many of us starting out will use the Auto ISO settings on our camera and that’s perfectly fine.

Setting ISO in Low Light

But what if we want the cleanest image possible even in low light?

It’s simple. You just need to lower your ISO, put the camera on a tripod or flat surface and use a longer exposure. Check out our posts on exposure and shutter speed for better understanding.

But once you’ve mastered that, you can create some cool long exposure images like these.

You may have noticed some cool blurring effects with those photos. What happens if you don’t want that?

That’s where the higher ISO settings will help. Anytime you want to quickly capture an image in lower light, raising your ISO will help.

If you have kids or pets in dimly lit rooms or just want to freeze the action of any photo, increasing the ISO can help here.

You won’t get the cleanest image possible, but it will definitely help you achieve the intended look of your photo.

Conclusion

The ISO Definition in Photography is not all that important. All you need to know is how to set your camera to high and low ISO to capture the best moment.

You also need to understand that the higher your ISO setting, the more noise your image will have.

BOOM. There we have it…

ISO checked off the list.

Let us know what other photography questions you have in the comments below. And if you still need more Tips on Camera Basic, check out these other great Photography posts. I’m Gideon van Niekerk signing off.