The Photographer's Trinity: Aperture, Shutter Speed, and ISO :: Digital Photo Secrets

The Photographer's Trinity: Aperture, Shutter Speed, and ISO

by David Peterson 26 comments

The Photography Trinity are three aspects of photography that go hand in hand: the aperture, the shutter speed, and ISO. Whenever you make a change to one, you have to make a change to the others in order to balance everything out. In this tip, we’ll have a look at how all of this comes together to create the perfect image.

You can achieve this effect by opening up the aperture. But when you do that, you also need to change your shutter speed or ISO.
Photo By: Bruce Guenter

What makes theses three a Trinity?

There's one thing all three have in common, and that is light. The aperture, shutter speed, and ISO speed all control the amount of light that makes it into the camera. When you adjust any one of them, you’re changing level of light exposure and making the image either more or less bright.

Let’s have a quick look at the way each of these affects light exposure:

  • Shutter Speed. When you adjust your shutter speed, you’re changing the duration of time the shutter stays open to allow light into the camera. If the shutter is open longer, more light will enter the camera and hit the sensor. But if you increase the shutter speed, the shutter opens for a shorter period of time and less light hits the sensor overall. This will result in a darker image.
  • Aperture. The aperture is the hole on your lens through which light travels before it hits the sensor. If you open up the aperture, more light enters the camera, and the image appears brighter. If you close the aperture, less light enters the camera, and the image appears darker.
  • ISO Speed. This is a number that determines the image sensor’s sensitivity to light. If it’s more sensitive, you’ll end up with a brighter image. If it’s less sensitive, you’ll end up with a darker image. ISO speed also impacts the graininess of an image. If you pick a really high ISO speed, the resulting image will be much more grainy than if you were to use a low ISO speed.

So there you have it. Each of these impacts the image in its own distinct way, but they always affect the amount of light that hits the image sensor on your camera. As you learn your way around manual mode, you’ll start to see it more clearly. An adjustment to one always requires an adjustment to at least one of the others.

Always think in sets of three

Every picture you take requires some combination of these three elements. That’s why you should always be thinking in terms of threes. There are multiple “correct” ways to take a picture using aperture, shutter speed, and ISO speed. Once you find one combination, the others are just a few clicks of the dial away.

Increase your camera’s ISO speed to get brighter pictures while indoors. This picture was taken at ISO speed 12,800.
Photo By: Mike McCune

Let’s imagine you’re shooting the sunset, and you get a really nice and colorful shot using a shutter speed of 1/250s, an aperture of F8, and an ISO speed of 100. Are there other ways to get a similar result? Of course there are! You just have to know how a change in one value affects the others.

What if you were to pick a slower shutter speed? What if you went with 1/125s instead? What would happen if you were to change that value and nothing else?

Because the shutter will be open longer, more light will get let into the camera. If you leave everything else unchanged, you’ll end up with a brighter image. So what can you do to get the same evenly balanced image? What can you do to make it “just right” again?

Well, you could close off the aperture a little more. If you change the aperture to F11, it will let in less light, and you’ll end up right where you were before you changed the shutter speed. You’ve just found yourself another combination that works. Write it down: 1/125, F11, ISO 100.

You could also modify the ISO to compensate, but because you’ve already set the ISO speed to its lowest possible setting, a change in ISO speed won’t really accomplish much of anything. You need to darken your image, not brighten it, and any increase in ISO speed will only result in a brighter image.

A lot of combinations are correct, but only one works the best

What you’re trying to find is the one combination that correctly expresses what you want to get across with your image. A lot of combinations will do, but the magic one has just enough depth of field, sharpness, and detail in all of the right places. To find it, you have to ask yourself what’s most important about the picture you’re taking.

Here’s another example. Imagine you’re shooting some action on a sunny day, and you want your star athlete to appear frozen in the middle of the action. A lot of shutter speed, aperture, and ISO speed combinations will do the job, but only a few of them will freeze the action in just the right way. The ones that will work undoubtedly make use of a fast shutter speed.

The ball is completely frozen in the air. To get a picture like this, you need to set the shutter speed to at least 1/500s.
Photo By: Tim Schapker

You know you need a shutter speed of at least 1/500s to get the action to freeze, so you might as well set your shutter speed to that value. Now it’s merely a matter of finding the right ISO speed and aperture to balance everything out. At 1/500s, not that much light is entering the camera, so you had better be using a wide open aperture or a bigger ISO speed.

With a little bit of experimenting, you should be able to find the right combination. You just need to know what you want first. Once you know you need a shutter speed of at least 1/500s, it becomes apparent that you’ll have less light to work with, and that means the other two parts of the trinity have to compensate by increasing the amount of light entering the camera.

Remember the connection between aperture, shutter speed, and ISO speed. It’s all about light. Once you understand this, you’ll be ready to make the change to full-time manual photography.

Most people think this post is Awesome. What do you think?


  1. Lucien says:

    i could relate to this post as i experienced it for myself. this post just opened my eyes more. my pics came out grainy, but then i realised that the ISO was set high. i think all your post are valueable and i learn alot from. thank you

  2. Debasis Banerji says:

    I am now using Panasonic Lumix FZ100 Long Zoom Camera. I found your tips on inter-relationship of Aperture, Shutter Speed & Film Speed (ISO) lucid and very helpful specially when opting to operate Manual Mode. I am interested io get Free Photography News Letter.

  3. Sam says:

    Thanks Dave, I always loved photography since a kid. Slowly I moved up the ranks to buy my first Nikon D5200, after my antiquated Olympus (point and shot type). I read online several articles about photography, but yours stands out. I now have a better grasp of shutter, aperture and ISO. Thank you thank you. Your the best, please keep up the work.

  4. Pam M. says:

    Great tips. I'm a novice to digital SLR's, just bought my first one. Lot's to learn, as the camera manual doesn't fully explain where to find certain functions for manual settings-very frustrating. What settings would you use for taking a photo through glass with subject under fluorescent lighting?

  5. Mini says:

    When ever I took photographs in manuel mode I got pictures with grains inside rooms especially the dark area in the photographs is with more grains.Can you please explain for me.My camera is Nikon D 70.

  6. Falcon44 says:

    great tips... I need to practice more so i can use all these tips... Thanks a lot...

  7. Uris says:

    I found this article to be extremely helpful. I cleared up some of the confusion I had concerning shutter priority, aperture priority and ISO. Thank you very much.

  8. David Peterson says:


    I don't know a camera that does that. Normally, you set the ISO as low as possible for the conditions, and then choose either speed or aperture and let the camera choose the other one.

    See my article on ISO for the settings I recommend for different lighting situations.


  9. Noelene says:

    Well, that explains a lot! I've really struggled to understand and master these settings but now I won't be so afraid to have a go. I recently photographed the lunar eclipse but had to get help from my husband as I could only get decent pics by using manual settings. Hurry up weekend so I can practice!

  10. liz says:

    thanks for the tips David, I am a novice, and that is my struggle right now, trying to balancing the three as mentioned, your tips are helpfuland easy to understand.

Leave a Comment

Your email address will not be published. Required fields are marked *