What is ISO

So What Is ISO Anyway??

So, What Is ISO Anyway??

Almost every digital camera has it these days, even your cell phone! So, what is ISO anyway?

Let’s take it back a bit, shall we? In the days of film, ISO (or ASA as it was called) was an indication of the film’s sensitivity to light. You would buy film based on the ASA, such as Fujifilm 100. An ASA of 100 requires more light on the subject than an ASA of 400, which is more sensitive to light.

So, ISO is a measure of the camera’s sensitivity to light.

In today’s digital world, ISO works the same way. Only now, instead of having to purchase new film, you just adjust the ISO setting in your camera! This applies to all cameras, from cell phones to Canon EOS 5D Mark III.

For example, check out this last minute groundbreaking photo of salt that I took using my Samsung Galaxy S5, with an ISO of 100.
Camera = Less sensitive to light.

So, What Is ISO anyway?? - ISO 100

Now if you go into your camera settings, there should be an ISO option. On the Samsung Galaxy S5 is looks like this:

So, What is ISO anyway?? - ISO on Samsung Galaxy 5

To show how much ISO can help, I changed this one to ISO 800. Camera = More sensitive to light.

So, What is ISO anyway?? - ISO 800

The difference is pretty clear. With a higher ISO, the camera is more sensitive to the light in the room and the photo appears brighter.

For your cell phone, it’s probably best to leave the ISO on auto.
However, if you’re ever in a situation where your photos are too dark or too bright, just check the ISO setting!

What is ISO anyway - Auto ISO on Samsung Galaxy 5

You: Thanks, Vivi! Is there anything else we need to know about ISO?
Vivi: Actually, yes! The higher your ISO, the more grain will appear in your photos. There is an art to adjusting camera settings so you get minimal grain, high light sensitivity, and the desired depth of field. ISO is only 1 of 3 of main adjustments photographers deal with. So, when we’re in the middle of a session and I say, “Relax for a sec, I’m just adjusting my settings!” you’ll know that ISO is one of them!

ISO in a nutshell

  • Lower ISO = Less light in photos
  • Higher ISO = More light in photos
  • Higher ISO = More grain in photos
  • 1 of 3 main settings for photographers

Keep an eye out for other By-The-Way Thursday’s on the other 2 main settings, Aperture & Shutter Speed!

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