10 Steps to Manual Mode: ISO Basics

young girl taking photos of a flowering tree with a DSLR camera
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This is the second part of the 10 part series: 10 Steps to Manual Mode.

You can access the series here—> 10 Steps to Manual Mode Series.

In this second part of the series, we are going to focus on ISO.

ISO is one of three parts of the Exposure Triangle that is very important when understanding photography.

I discuss the basics of the Exposure Triangle in this post—> Exposure Triangle Basics for Shooting in Manual Mode

What is ISO?

ISO refers to how sensitive the sensor of your camera is to the light.

Most people want to shoot with as low ISO as possible. This allows for the best quality of photo with the least amount of noise. If you are shooting on a sunny day outside, then it is easy to use a low ISO.

But if you don’t have a lot of light, you may need to increase your ISO. Don’t sacrifice the quality of a photo just because you don’t want to change the ISO number.

How do we use it to take better photos?

ISO controls the amount of light you let into your photograph.

So in order to use ISO at it’s best, you want to use the lowest number possible for ISO without sacrificing the quality of your picture.

You should experiment with your camera to see how far you can push the ISO before the picture starts to get grainy. This will be different for every camera.

For my camera (because it is an older model), the realistic ISO number I don’t want to go past is 1600.

But for newer cameras, some of them can handle 3600 or higher without noise. It just depends. The software is getting better every year.

Let’s take this photo above as an example. It is straight out of the camera. That means there is no editing, straightening, sharpening or noise reduction. This is taken inside my kitchen with no window nearby (there is a sliding glass door in the next room that is open to the kitchen).

I want to show you my thought process as I figure out what setting work best. The settings are at the top of each photo:

Photo #1: 

In this photo, I have my ISO at as low as it can go: 100. But as you can see, it isn’t bright enough and by hand holding it at 1/6th of a second, it isn’t super clear.

Photo #2:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

So with this one, I doubled the ISO to 200 but increased the shutter speed to 1/50th of a second. This makes the words a little clearer but the photo is still too dark.

Photo #3:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

On this photo, I increased the ISO to 500 and the shutter speed to 1/80th of a second. The words are clear, but the photo is still too dark.

Photo #4:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

Here I increased the ISO, but kept the other settings the same. Still too dark.

Photo #5:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

I doubled the ISO again here and it looks great! This might be a keeper!

Photo #6:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

In this last photo, I doubled the ISO again with not much difference, except I introduced more noise. That’s not what I want!

Introduction of Noise:

Noise is grainy or spottiness in your photo from the camera not having enough light to take the photo. You can tell the difference in these 2 photos. Noise usually starts in the shadows and if you keep pushing it it will cover the whole photo.

ISO 1600:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

There is a small amount of noise in this photo, but it isn’t too noticeable. Don’t forget that these are SOOC, which means I haven’t used any noise reduction software here.

ISO 3200:

a photo of farm fresh eggs in a vignette of a farm animal statue and sign

You can definitely notice more noise in this photo and we haven’t added much more light in contrast to the one above.

So the winner of these photos is photo #5: ISO 1600 Aperture 5.0 SS 1/80. Of course I could have introduced more light to the situation to decrease the ISO, but I wanted to show you the difference in settings on this photo.

How does ISO affect the exposure triangle?

Start with your lowest number ISO on your camera (usually 50 or 100).

Then set your aperture and shutter speed for the shot you want to get.

Then come back to ISO if you need to and bump it up to get the amount of light you need in the picture.

3 Tricks to Keep Your ISO low:

  1. Use a low shutter speed- If movement isn’t part of the vision for your photograph, use a tripod to stabilize your camera. This will allow you to let more light in the shot by lowering the shutter speed.
  2. Add in more light- Are you shooting indoors? See if you can shoot by a window or other light source to add more light to the shot without raising the ISO.
  3. Use a wider aperture- Still need more light? Decrease your aperture number to allow more light in the shot as well.

ISO is one of the 3 parts of the exposure triangle and it is crucial that you know how to use it properly to make a well exposed photo. By keeping the number as low as possible for the amount of light you have, you can take a photo that is well lit but not noisy or grainy. This is the key to using ISO properly.

Action Steps:

  1. Use the lowest ISO possible for your lighting situation.
  2. Test your camera to see how high you can push the ISO without introducing noise or grain into the photo.
  3. Try to get it right in camera: It is better to use a higher ISO in camera than to try to bump up exposure later in post processing.

This is the second lesson of ten that will be coming in the next 2 months.

Next week we will talk about shutter speed and how to use it properly for great photos. Click here to go to the next lesson —> 10 Steps to Manual Mode: ISO Basics.

Shooting in manual mode on your DSLR is important for every amateur photographer to learn. Knowing how to balance the 3 parts of the exposure triangle (including ISO) is the key to doing it right.

It will take many hours of practice before you get it right, but it will be worth the trouble, I promise!

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What is the ISO your camera goes up to before it introduces noise? Let us know in the comments below. And if this post was helpful, please share. Thanks!



man taking a picture with a monopod and DSLR camera

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