What is ISO in Photography?

ISO stands for International Standards Organization. Simply put ISO is how sensitive the sensor in your camera is to the light that hits it. The lower the ISO the lower the sensitivity.

In the film days you could buy film with various ISO levels. It is a lot easier to adjust nowadays than it was then!

ISO is measured in set numbers. These numbers double each time you increase the ISO. 100, 200, 400, 800, 1600 and so on.

These are the same on most DSLRs but sometimes have a different lowest value. Your camera might go as low as ISO 50, 100, or 200.

It doesn’t matter, all you need to know is whichever the lowest number you can select is for your ISO this is the least sensitive to light the sensor in your camera can be.

What is ISO used for?

ISO is part of the exposure triangle (aperture, shutter speed and ISO). We can adjust any of these to suit the needs of the environment we are in or what we are photographing. If shooting indoors or in low light, increasing the ISO will enable us to use a faster shutter speed (by making the sensor more sensitive to light), helping us get a proper exposure and hopefully a spanking photo.

Even if you aren’t in low light but want a faster shutter speed to freeze some wildlife or action then increasing the ISO level will be just what you need to capture that perfect photo!

What ISO should I use?

You should always try to use the lowest ISO as you can. This is because as you increase the ISO level on your camera the more noise you will get in your photos.

What is noise? Noise (digital noise) is the little bits of grain and interference in a photo when taken at a high ISO.

Take a look at what happens when we take the same photos at different ISO levels.






As the ISO increases the picture quality reduces. This is why I said try and always use the lowest ISO possible. But don’t be afraid to take photos at higher ISO as it is far better to not miss that moment and have a bit of noise in the photo – than to completely miss it entirely!

How do I change the ISO on my camera?

It’s really easy to change the ISO on your camera. Most cameras have a dedicated ISO button. Press it as use the scroll wheel (depending on your camera make), to change the ISO level. Some other cameras you might have to go into the menu to change it. Just do a quick google search if you are unsure.

Here is a short video to show you how I change it on the camera I use.

Once you understand how to use ISO to your advantage you will start to take photos you never thought were possible. It could just be the key to unlocking your photography potential!

If you are struggling with the basics why not try my free photography course here.

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