What is ISO in Photography

January 01

7 min. to read

What is ISO in photography and why does it matter so much?

If you don’t understand what ISO is and how it works, then you might find it difficult to take good pictures. Afterall, ISO is one of the three pillars of photography (Aperture and Shutter Speed being the other two) and every photographer, no matter how experienced they are, should be well aware of what it is. This would allow you to get the most of your camera so that you can produce stunning images.

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This article is written for beginners which is why we did our best to explain ISO in layman terms. However, before expressing interest in  ISO, you should have know-how on how DSLR cameras work. With that being said, let’s get started: 

What is ISO?

To put it simply, the level of sensitivity of your camera sensor to available light is what we call ISO. To explain further, a lower ISO number means the camera sensor is less sensitive to light its receiving while a higher ISO number means the sensor is highly sensitive to light.

However, remember that the sensitivity can vary between sensors as there are a plethora available in the market. Still, DSLR camera sensors aren’t that complicated and the same ISO settings generally apply.

The sensors in a camera are the most expensive and important component, which allows it to process light into an image. You can capture images in a low-light environment when your ISO is set to higher numbers. But remember, higher ISO levels lead to grain and noise penetration in your pictures, which doesn’t quite look nice when you zoom in or print a large version of them.

Here is a live example:

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ISO 100 and ISO 3200 Comparison

You can see that a higher ISO number yields more noise and graininess whereas a lower ISO number results in a smooth and freckle-free image. 

Getting to Know ISO in Detail

Every camera has a basic ISO number which produces the highest image quality, without adding graininess or noise to the picture. These ISO numbers vary depending on the camera manufacturers.

For example, Nikon cameras, such as the NikonD5100, has an ISO base of 200. Canon cameras, on the other hand, have an ISO of 100, which is the minimum ISO number. Usually, most professional photographers stick with the minimal ISO number and generally prefer not to stray too far from ISO 800 unless absolutely needed. This is because going beyond ISO 800 would add graininess to an image, inevitably resulting in loss of image quality.

ISO numbers have a two-multiple increment in every value, meaning that every ISO number increases by the power of two. This is why the general ISO sequence is: 100, 200, 400, 800, 1600, 3200, 6400 etc.

In simple terms, each step between these numbers doubles the sensitivity of the sensor. So, for instance, ISO 1600 is sixteen times more sensitive to light than ISO 100, and so on and so forth. You should know that ISO numbers affect how fast a camera can capture light to produce an image. For example, if ISO 100 takes the camera a second to take a photo then:

  • ISO 200 would take 1/2 of a second 
  • ISO 400 would take 1/4 of a second 
  • ISO 800 would take 1/8 of a second 
  • ISO 1600 would take 1/16 of a second 
  • ISO 3200 would take 1/32 of a second

Choosing the right ISO number can mean a world of difference in photography. For example, if you choose a lower ISO number in low-light conditions, it would take time to produce the image which can make it blurry. But if you have a tripod, the same setting would result in a beautiful, soft image (if its landscape you’re portraying). However, a higher ISO number (preferably not more than 800) would produce a crisp image and can help freeze motion since it takes less time to capture the image. 

Using ISO the Right Way

Generally speaking, using a lower ISO setting always produces better photos. We recommend using not more than ISO 800 in low-light conditions and ISO 100 in well-lit conditions, whenever possible. Using the lowest ISO setting would result in a more detailed photograph that yields the highest image quality. Many photographers take photos in ISO 100 or even 200 in low-light conditions. They use a tripod to balance the time it would take for the camera to capture the image. However, these photos are only taken for landscapes. These setting shouldn’t be applied to portraitures as you would just frustrate the subject.

What if you want to capture something in the dark and have to go with higher ISO numbers (above 800)?. In this case, it is advisable to sacrifice image quality in order to take that shot.