Mastering the Exposure Triangle for Newbies

When I first got my digital camera, words like Aperture and ISO were foreign to me, and it took me a couple of weeks of reading and studying a lot before the lightbulb turned on in my head. You might be feeling a little confused, and you may even feel like you will never get your camera out of Auto mode, because it’s just too hard to understand.

So, if you are unfamiliar with your camera, or just starting out, you might appreciate a little explanation of the basics. Sometimes reading about these things in slightly different words helps something new to click each time.

Introducing the Exposure Triangle: Aperture, Shutter Speed, and ISO

These three things work together to expose your picture perfectly, and after experimenting for a while, you may even find that you can use your knowledge of these three things to manipulate your picture for different effects.


The aperture or f-stop is how wide open your lens is. Imagine a hole: if it’s open just a teeny bit, there won’t be very much light coming through. If it’s a big hole, lots of light will come through. The tricky thing with aperture is that often confusing numbering system.

  • SMALL numbers (like f/1.8) = wide open aperture (large opening).
  • BIG numbers (like f/22) = small aperture (teeny opening).

That confused the heck out of me at first, but now it’s second nature. It will become second nature to you too, after some practice!

Another thing that can be affected by aperture is depth of field, or how much of your picture is in sharp focus. A wide open aperture (small number) will make less in focus, and a closed down aperture (big number) will make more in focus. Let’s look at some photos that demonstrate depth of field:


With the aperture set to f/3.5 on the left, you have a blurrier background (my favorite). Also notice that the shutter speed (1/640th) is fairly HIGH, we’ll get to this later.


A little bit smaller aperture (bigger number), makes the background come into focus a bit more, and the shutter speed is slowed down.


See what I mean? If you want to play around with Aperture, try putting your camera in Aperture Priority mode (A on Nikon, Av on Canon – if you have a different camera, check your manual).

Now, remember that all three parts work together? You probably started seeing how if you noticed the shutter speed changing with each of those different aperture values in the pictures above.


The shutter speed is how fast the shutter opens and closes. If the shutter is open longer, more light is let into the camera. If it opens and closes really fast, less light is let in.

If you have a wide open aperture, your shutter speed will need to be faster, because you’re already letting a lot of light in the lens opening. If your aperture is small, your shutter will need to move slower, so there is more time for light to get to the sensor.

If you want to freeze the action, or hand-hold your camera, then a faster shutter speed is needed. If you want to create blur, then you need a slower shutter speed. For example:


The vehicle in the photo on the left was driving past my house quite fast, but since I had the shutter speed set to 1/2000th of a second, it froze the action. It looks like the vehicle could be sitting still in the middle of the road.

The truck on the right is a blur going past, but everything else is still. 1/10th of a second was slow enough to blur the truck as it sped past. Notice the f-stop. Since the shutter was open for so long, the opening in the lens needed to be smaller to balance the exposure.

Try putting your camera in Shutter Priority mode (S on Nikon, Tv (time value) on Canon) to experiment with different shutter speeds. As you play with these different priority modes, notice what the camera chooses for the rest of your settings. The more you pay attention to these things, the more knowledge you’ll have to be able to set everything yourself in the future.

Okay, so now you’re probably asking, how does ISO fit into all of this?


The ISO is your camera’s mood. It can be all uptight and picky, or it can be easy-going and laid back. If you have the ISO set to a low number (100) your camera will want light, and plenty of it, because it’s going to take a smooth, crisp picture, and this requires perfect conditions. If you have your ISO set to a high number (3200) it can handle low light, because it’s not going to work as hard – a noisy (grainy) picture is good enough for Mr. High ISO.

So, how does this apply to your photography? Let’s say you wanted to take a picture in the evening, and you don’t want to use a flash. Just bump the ISO up, and it will allow you to have a faster shutter speed, or a smaller aperture (bigger number) and still accept the light conditions to expose correctly. Or, if you’re taking pictures at a sporting event, and you want to make sure you catch that action, but the light isn’t great, bump the ISO up. Or you may even want that moody grainy effect (it can be really cool)!

If you ever get frustrated because there’s just not enough light, and your pictures are blurry because the shutter speed isn’t fast enough, and you’re about to scream – just remember to bump the ISO. You could also leave this on Auto, but I usually don’t. My camera always seems to choose a higher ISO than I feel it needs. However, don’t forget to put it back down after you’re done. You don’t want to take a whole bunch of photos in the middle of the day at a 3200 ISO because you forgot to change it after your evening indoor party photos the night before.

Here’s a little demonstration:


ISO 3200

The photo above was taken in a very dimly lit room. Notice the digital noise?Notice the crispness of the photo below?


ISO 100


Well, that’s the exposure triangle in a nutshell. I hope this helped, especially if these three exposure factors have been confusing to you in the past. Please ask any questions in the comments, and I’ll answer them the best I can.

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