ISO Sensitivity - The Basics

This is a translation of a blog entry by Masatsugu Murakami.

Hello everyone,

I’m the photographer and photography consultant for Glams, Masatsugu.

Today I am going to explain about ISO sensitivity and how it works.

If you have picked up a camera before and spotted a setting called ISO which made you think ‘Huh? What’s that?’

Well, you’re not alone.

Hopefully my explanation will be easy to understand, so let’s master ISO together.


1. What is ISO sensitivity?

2. If you can help it, shoot photos with low ISO sensitivity.

3. ISO sensitivity when shooting product photos

1. So, what is ISO?

If you look below this is a ISO sensitivity setting screen, as you can see you can select from AUTO, 125, 300, 400, 800, 1600 and much more that you can choose from. So, to explain it simply ISO is a setting

To increase the value of light so you can take photos even in a dark environment.

For example, if you take a photo in a slightly dark room and you shoot at ISO100, the photo will turn out something like this:

It turned out a bit blurry, huh.

(Current setting is set as A-Mode (Aperture priority mode))

Whilst this, has been set at ISO3200:

There we go, complete clarity!

With ISO sensitivity set to a higher value, we can easily amplify the light setting in the room without much effort. Digital cameras capture light through their lenses, then generate images by the varying degrees of light through sensors.

If the amount of light taken in is too small, the image will be dark.

When the shooting mode is A mode (Aperture priority mode), it tries to take in more light automatically so as not to make the image dark.

In order to capture sufficient light, the shutter speed is slowed down, but if the shutter speed becomes slow and you take a picture by hand, you will cause camera shake.

In situations such as these, if you have the ISO sensitivity with aperture up, you can shoot a sufficiently bright photo because it will amplify the light even if you don’t slow down the shutter speed (without much light).

You will also be able to achieve a great photo indoors and/or at night with these same functions.

2. If you can help it, shoot photos with low ISO sensitivity.

As handy as ISO sensitivity is, there are some demerits. That is with raising the aperture you could be decreasing the quality of your photo.

How much is depending on the type of camera you have but, to take a beautiful photo without much noise you will have to lower the ISO sensitivity. If you wish to take a photo in a dark area, with the ISO sensitivity amount on low, I’d suggest shooting your photos with a tripod instead of by hand. Have you wondered why your smartphone takes noisy photos at night? It's because the camera has automatically set it's ISO setting high to pull in light since it can tell you are shooting in a dark environment.

For example the photo below I shot against a night sky, with my camera on a tripod and the ISO on the lowest setting. By doing this I was able to take a beautiful photo.

Saying that, the cameras now available on the market has really improved. There are now camera models for sale now that with this same shot at ISO3200, the noise level isn’t noticeable. In a dark environment without use of a tripod, and ISO sensitivty set to high you will have no excuses to say that the photo quality was bad due to high aperture thanks to improving camera technology.

3. ISO sensitivity when shooting product photos

When shooting the perfect product photo, you’ll quickly notice that just relying on your camera that there’s something missing.

In my opinion I always use a lighting set up when shooting product photos because the results are far better than shooting with a camera alone.

If you’re going to shoot product photos, get the best lighting setup that you can so you can keep shooting at a low ISO setting.

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