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

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

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 F9, 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, F9, 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.

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About the Author ()

David Peterson is the creator of Digital Photo Secrets (this site, and the course) and loves teaching photography to fellow photographers all around the world. You can follow him on Twitter at @dphotosecrets or on Google+.

Comments (25)

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  1. 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.

  2. 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.

  3. 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?

  4. 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.

  5. Falcon44 says:

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

  6. 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.

  7. @Daniel

    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.

    David.

  8. 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!

  9. 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.

  10. Daniel says:

    Dear David: I wonder if there is a camera able to chose automatically IO value after i set both speed and aperture, in order to get the right amount of ligth keeping fixed those otehr parameters?
    Thanks a lot

  11. Sue says:

    Geez people. Lighten up. Okay, so it possibly wasn’t the best of examples. But at least now we all know the importance of getting the light right.

  12. Tracy says:

    Just wanted to say a big thank you for sharing your talent with folks like me…thats kind! And Im smiling at the conversation about the Holy Trinity…maybe its time you checked it out for yourself David…check out the one who claimed to be ‘The Light’…now thats a strange thing isn’t it?! Johns gospel is a good place to start. Thanks again

  13. Rose says:

    I wish you had submitted three videos ISO,aparture shutter speed etc to make your point seeing is beleiveing…….Your three connectins compaarions was also lost on me..
    As they say in Michigan “SHOW ME” please
    Thanks

  14. Kees says:

    Thanks so much learning so much about photography that I never new about before

  15. Elvin says:

    Hi, Well, ‘holy’ trinity is a bit ‘to far’ for me, there is nothing holy about it although on some modern equipment like Canon it sometimes look like it is made by God (and in my opinion the subjects and light may be, but not the camera).
    While reading, I noticed that you made a little calculation-err. instead of moving from aperture (or diafram.) f/8 to f/9, you would change to apperture f/11 or f/16 to get the same effect. Aperture is put into ‘logical stops’ and on this scale the normal stop is from f/8 to f/11, then to f/16.
    to put it simple: when you change the shutterspeed one stop upward, you should change the aperture or the ISO speed one stop downward – as long as you don’t use flash.
    When you keep the ISO the same, you can keep changing the aperture and the shutterspeed with each other in these stops. if you change the shutterspeed one stop up (for instance from 1/125 to 1/250 of a second), you should thus open up the aperture more (from f/16 to f/11) to keep the same light on the sensor. if you take 2 stops (1/125 -> 1/500), you should from f/16 to f/8
    If you keep one of these the same, you can work in ISO-speed: if you keep the same aperture, and make the shutterspeed “the half”, you should change the ISO-speed “double”: 1/125 sec., f/8, Iso 200 is the same effect as 1/250 sec., f/8, Iso 400.
    Since also ISO is in stops it makes logical sence: ISO 400 takes the half amount of light (one stop from 200) as does ISO 800 takes 1/4th of the light of the 200 film (two stops from 200).
    I hope this makes some things clearer for the “novices”. Elvin

  16. Carole says:

    I am taking some photo’s of blind and partial blind people with learning difficulties indoors, flash is a no no, and they have sometimes jerky movements – what would be my best setting? Challenging assignment for me!

  17. siddharth says:

    instead of using holy trinity JUST SAY TRINITY& IT WONT HURT FELLOW CHRISTIANS
    BT ALL SAID & DONE- IT LIKE IT , THE WAY U HAVE EXPLAINED ALL OF IT’
    AL D BEST DAVID PETERSON

  18. Howard Menzies says:

    This subject displays the reliance many people have on the automatic features of digital photography. Those of us who used film were accustomed to film speed, aperture, shutter speed, focus, depth of field and composition to achieve the desired effect. What most of we oldies need (many of whom actually developed and printed our B & W photos), is the ability to understand and quickly adjust digital cameras. As a digital novice who still uses film on occasions, I find the multi-screen, multi-option process of setting the camera to create the effects sought a real challenge. As a consequence, my digital is usually set on “intelligent auto”, and if I want to isolate a subject as you have done with the bird, then I use the zoom function. Oh, and by the way, what’s my “URI”?

  19. Roger Urquhart says:

    To all following Davids tips and advice…. 18 months ago I started to receive Davids photography tips and studied what he said, put it into practice and improved no end. I had a beat up D40 from nikon, I now have a D700 fitted with a 50mm f18 prime and would never want/ need another Camera as my skills have increase 10 fold, love you work and advice David, please accept my thanks for making it happen.

  20. To: Patricia and Jim and anyone else I may have offended with my use of the “Holy Trinity” wording.

    I do not mean any offence, and certainly did not mean to imply that the relatedness in photography terms has any relationship to Christianity.

    Please accept my apologies.

    David.

  21. Mike McCune says:

    Thankfully a lot of SLRs have really good Auto ISO modes but in cases like that photo above of me I had to manually bump it up to 12,800 since the auto mode only goes up to 1600.

    In really low light or extreme conditions you often have to tell the camera what the right thing todo is. experimentation is key

  22. Patricia Singh says:

    The Holy Trinity ‘s inter-connectedness is a lot more profound than merely a balancing act between Aperture, ISO and Shutter speed. Please kindly refrain from using that to describe a simple technicality of photography.

  23. Heather Iles says:

    Thanks for explaining about shutter speeds which I found very helpful, especially when taking sport pictures.

    Your suggestion for using a shutter speed of 1/500 for sport is fine, but what nunber aperature and what number ISO would you use with this.

    You must remember that most of us are complete novices. Although I have an LSR camera I still don’t understand much about the three “Holy Trinity” principles. Perhaps you would explain the different number settings that correspond with the different shutter speeds. Is there a table to study? Please point me in the right direction.

    Many thanks.

    Heather

  24. Glory Phuthwa Ndlazi says:

    your courses are benefitting and they are the shrpening skill and tool

  25. Jim Cornish says:

    Except for the “three” connection, your comparison of exposure to the Holy Trinity is lost on me, especially when you get into describing the connection between ISO, aperture and shutter speed. While changing one affects the other, the same cannot be said for the “Holy Trinity”.

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