Exposure Settings - What Are They & How Do They Work?

The Exposure Triangle

What is the Exposure Triangle?

When you are starting out with your camera, digital photography it can be a bit overwhelming to deal with all those various available settings. The first thing and I'd say the most vital step is to learn about is the exposure triangle. Sounds about as mysterious as the Bermuda Triangle right? Actually it is reasonably simple - it's the relationship between your shutter speed, your aperture and your ISO setting. The 3 work together to create a properly exposed photograph. Exposure might best be described as the amount of light that hits your camera sensor for a particular duration of time. 

Those very same rules applied when everyone shot with 35mm film cameras - except that the light was exposing on actual film, not  a digital sensor. That's how I got started way back in my high school photography club, shooting with a 35mm film camera and then later developing the pictures in a darkroom. The challenge with that was twofold - you had to hope that your exposure settings were exactly right, and you also had to choose the correct ISO film for the conditions and scenes you were capturing. The digital camera sensor now acts as our "film" and it's a huge advantage! Now we can play with all our exposure settings and see the results immediately, and then simply adjust those settings as necessary. 

 The reason we call it the exposure triangle isn't really that mysterious - it's  because when you adjust any one of the 3 exposure settings, then one or both of the other 2 settings must also change  in order to get the same exposure. If you overexpose, you get those super bright photos that have absolutely no detail. If you underexpose you get those photos that are just way too dark. So...learning this relationship between shutter speed, aperture and ISO will be the foundation of your ability to capture great photographs.  Let's now  review the basics of each of 3 elements.


What is Aperture? 

This is most simply described as the ‘the opening in the lens.' When you hit the shutter release button of your camera a hole in your lens opens up that allows your camera image sensor to catch a glimpse of the scene you’re capturing. The aperture you choose sets the size of that hole. It's fairly straightforward - the larger the hole in your lens the more light that gets in,  the smaller the hole in your lens the less light that gets in. 

So obviously the aperture setting will affect the overall brightness of your photo - but here's another consideration - it also controls something that's called depth of field.  That is the range of distance that determines what will appear sharp in your photograph and what will appear blurred. When the background of your image is blurry, you have what we would call a shallow depth of field - that's when the point you are focusing on is quite small. Typically, the larger the hole (larger aperture) the more blur effect you will get  If you take a picture of a landscape and the whole thing is in focus from front to back, that is called a deep depth of field and your aperture setting would need to be a smaller hole. A large area of the image is sharp and in focus. Different lens models have different aperture capabilities but you will always control your aperture setting from the camera. 

What is Shutter Speed? 

 The shutter is arguably the most basic component of any camera. When you push the shutter button you snap the picture.  It’s more or less a curtain that covers your camera’s sensor that opens to allow light in, and closes to stop it. Because the shutter speed controls how long you are letting light into your sensor, your choice of shutter speed will determine a number of different effects for your photo. 

Here's a couple of simple examples - we can use a really fast shutter speed such as 1/500 to freeze movement or action, a bird in flight or your children running across a lawn. Or we can use a long shutter speed to capture movement, star or light trails, or to capture very dark scenes without having to increase the ISO or make the aperture smaller. The longer the shutter is open, the more light that gets in. You can create  very creative photographs with various shutter speed settings, but understanding how to adjust the other 2 elements as you capture your subject or scene is the key to pulling it all together.

What is ISO? 

 ISO is probably the easiest of the 3 elements to understand but it can be tricky to adjust it in concert with your other 2 triangle settings to get the correct exposure. ISO is simply how sensitive your camera sensor is to capturing light. A low ISO number means your digital camera sensor is less sensitive, and a high number means it is more sensitive. .A lower ISO makes it so that the sensor does not need to collect as much light to make a correct exposure, an example would be shooting outdoors on a sunny day. Your ISO setting would typically be  100-320. A higher ISO would be helpful when you are taking a picture in a fairly low light environment and that could range anywhere from 800-3200 depending on the specific light conditions.  

Always an important consideration with your ISO setting it the amount of "noise" that will appear in your photo. Noise is a tern that essentially means the amount of grain in your image - that's when you see lots of speckles in the photo and it seems less sharp. Here's the basic guideline - the lower the ISO the sharper the image will be. So - use higher ISO if you need to, but lower is typically better.  Auto ISO is a good setting to start with - see what your camera is choosing before making any adjustments. 

How do they work together - how do I decide?   

As you reviewed the 3 exposure triangle settings you may have realized that while each of the three variables work very differently, they can all effectively produce the same result. They allow more or less light to reach the sensor. It’s really simple as that. So you may ask “why would I change one over the other?” This is the point where the technical becomes art. Each exposure variable has its own characteristic that it brings to the table. That's where continued learning and lots of experimentation and comes in. That is truly the greatest advantage of digital cameras, you can play around with your settings in various settings to find what works best for the photograph you have in your mind's eye!

We cover the 3 exposure triangle settings in our beginner workshop and we practice as we go so that you can begin to learn the relationship between shutter speed, aperture and ISO. Join us at our next beginner workshop in Regina, Saskatchewan