We’ve talked about aperture...and shutter speed...and ISO. Well now it’s time to talk about how they all affect each other. How they play together. And that is called the Exposure Triangle. No, I didn’t say the Bermuda Triangle.

The exposure triangle is simply the relationship between those three variables of exposure: aperture, shutter speed, and ISO.

No reason to panic here. Nobody is asking you to start shooting in manual mode and figure this all out. We’re in this together. We’ll start with a little replay of each of those variables, and then dive into the love, I mean exposure, triangle.

You got this. It’s not as scary as you think. It really isn’t anything like the Bermuda Triangle. Trust me.

Okay, let’s start with our old friend aperture. Remember, aperture affects depth of field, or how much of your image is in focus. The smaller the number = the bigger the hole in your lens = the more light that comes into your camera.

Now shutter speed is how long your camera’s shutter stays open. The faster the shutter speed, the less light that comes into your camera, and the more likely you’ll freeze motion rather than blur it.

Are you with me so far? All of this sounds soooo familiar, doesn’t it?

Moving on to ISO. That is what you use when you want to increase your camera’s sensitivity to light. So when it’s getting darker, or you go inside, then turning up the ISO number will help you make brighter photos.

Let’s summarize it here:

APERTURE:

Small # = big hole = more light

Large # = little hole = less light

SHUTTER SPEED:

Fast = freeze motion = less light

Slow = blurred motion = more light

ISO:

Small # = more light outside

Large # = less light outside

And here’s why all of this is so important. If you decide, “hey I want a really deep depth of field of this mountain scene so I can get everything in focus, from the rocks in the front to the mountains in the back; so I’m going to choose f/22”. Okay great. What that means is that f/22 is a REALLY little hole, so not a lot of light is coming in. Which is okay IF you have a bright and sunny day outside. You should be fine.

Another example of bright and sunny. Aperture f/8, shutter speed 1/400 second, ISO 100.

BUT what if it’s a cloudy day, and you choose f/22? Well, if the ISO stays at a low number, then your camera is going to have to compensate by getting more light from somewhere else. Why? Because you need a minimum amount of light coming into your camera to make the photo. Where is that light going to come from? Shutter speed.

If you choose aperture of f/22, ISO stays at say 100, then your camera will say “well since we need more light, let’s really slow down that shutter speed”. Because remember, a slow shutter speed = more light.

And if you remember when we talked about shutter speed...if it gets TOO slow, then it’s hard to handhold your camera steady enough. And what happens then? Blurry photos. Yep, that’s right a slow shutter speed can also = out of focus photos. Which sucks. I know, because I’ve had a whole lot of those.

This is back in the day, when the exposure triangle completely baffled me. Which meant a lot of out of focus shots due to slow shutter speed. Aperture f/6.3, shutter speed, 1/8 second, ISO 200.

That was before I really paid attention to all of this. I shot in aperture priority and figured my camera was smart enough to figure it all out. And it is. Sort of…

It is, until the priority between increasing the ISO and changing the shutter speed comes into the equation. Your camera seems to slow down the shutter speed before increasing your ISO, for some reason.

So even if you’re shooting in aperture priority mode, it’s important to keep an eye on your shutter speed. If it starts to get too slow? Then it’s time to increase your ISO. Why? Because that brightens things up, and lets you keep your aperture where you want it and still get a fast enough shutter speed.

Now sometimes, even increasing the ISO isn’t enough, if there’s a real shortage of bright light. In that case, you might have to make accommodations with your aperture too. If you lower your aperture a few notches, like from that f/22 example down to say f/16, or even f/11, you’ll get a whole lot more light in there. And that way you’ll have more flexibility with your shutter speed, without having to really crank up the ISO.

When it’s not quite so bright and sunny, then a little bump in ISO helps keep your shutter speed where it needs to be. Aperture f/8, shutter speed 1/80 second, ISO 320.

WHEW! I know it’s a lot. It can be overwhelming. And if you’re thinking, why the heck do I need to know this if I don’t plan to shoot in manual?

Well just like I said before, even if you shoot in aperture priority mode, sometimes your camera isn’t as brilliant as you’d like it to be. So it really comes down to having a general understanding of all of this, so you don’t end up with blurry photos.

And all of these variables are dependent on the others. Shooting a shallow depth of field at f/4? Well then a whole lot of light is coming in, and that means a faster shutter speed and lower ISO. Fast shutter speed to freeze motion? Well, then you’ll need a larger aperture hole (smaller number) or increased ISO to let enough light into your camera.

See it’s all about how much light is coming into your camera. If you increase the light in one area, you need to decrease it in another. And vice versa.

Going inside? That will take a higher ISO to give you the aperture and shutter speed that you’re looking for…Aperture f/4, shutter speed 1/60 second, ISO 1250.

If this is confusing, I know something that can help. Well, a couple of things. First of all, get out your camera. Put that sucker in manual mode. Yeah, I know...that’s terrifying. But it’s just for practice. It doesn’t matter if all your images are terrible.

Now put the aperture on say f/4, and ISO 100. Now try a whole lot of different shutter speeds and see what you get. Now keep the aperture on f/4 and change the ISO to say 1600. Now try a whole bunch of shutter speeds and see what you get.

See what I’m doing here? It’s learning through experimentation. You won’t break your camera. You won’t mess anything up. You’ll just create a whole lot of bad photos. Which is how you learn. Yes, that’s right. Making bad photos is how you learn.

Because making those bad photos is how this will all make sense. And then when you finally go back to Italy?? You’ll be a master of the exposure triangle and your photos will be freaking awesome.

Need a little more of a refresher on the exposure variables? Here’s my blog post on ISO. And here’s the one on aperture. And finally check out the post on shutter speed here.

Now get out that camera and have fun! And make some terrible photos in the process.

The Exposure Triangle Made Easy

Ready to create photos you LOVE?