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ISO For Dummies

So you’re just getting into photography or maybe you’ve been snapping photos for months now with no real understanding of what ISO is. Luckily for you I’m going to break it down in an easily understandable way so that you won’t be a dummy anymore! Don’t take offense, I was a dummy too (still am sometimes).


What is ISO?

ISO allows you to take photos in darker situations and still get a useable image. It is one of the three basic camera settings that will help you brighten or darken a photo. Without getting into the other two, I’ll tell you that they are aperture and shutter speed. With that, let’s move on.

As I mentioned, we can use ISO to our advantage to take photos in poor lighting conditions but as with anything in photography, there is a trade off. A photo taken with high ISO will show a lot of grain. This can also be described as noise. If there is too much noise, the image may not be useable. For that reason, you should never use ISO to brighten your photo unless the exposure you want can’t be achieved with shutter speed and aperture.

ISO Values Explained:

ISO typically ranges from 100 to 6400 on the majority of the cameras on the market today. ISO 100 in proper lighting conditions would produce a really clear and crisp result. ISO 6400 would be extremely noisy in low light or over exposed on a well lit day.

Most cameras have a native ISO which is the setting in which the camera produces the best images. Typically 100-200 is the setting for most brands.

Here is a quick rule of thumb. A photo taken at 800 ISO will be twice as bright as a photo at 400 ISO. Double the ISO, double the brightness.

The Coolest Trick to Remember About ISO!

Are you ready for this? I really wish I could remember where I learned it because it has stuck with me for years.

Picture this. Inside your camera are ISO bees (or light bees). Their job is to fly out of your lens and gather enough light needed to expose your photo, then they all fly back into the camera with the light needed. Still with me?

Now let’s say it’s a bright sunny day. You only need about 100 ISO bees to fly out and gather light. Therefore when they fly back into the lens, they won’t produce much noise because there were only 100 of them.

On the flip side of that coin, if it’s dark and it takes 800 ISO bees to gather all the light needed to keep that photo exposed properly, then when all 800 fly back into the lens, there is going to be some more noise.

Pretty cool way of thinking about it right?

I would love to hear what you think of the bee analogy in the comments below. I would also love to answer any questions you might have regarding when certain ISO should be used and what the advantages and disadvantages are trying to shoot as low as possible.

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Kanchan Yadav
Kanchan Yadav
29 may 2020

Really good article Brian. It’s really helpful for a beginner to understand the concept of ISO. Also bee analogy is really apt for this situation 👍🏻

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