I have taught photography classes for years, and mastering exposure is one of the hardest concepts to grasp. Let me teach you, what I have taught hundreds of students as I helped them to truly master exposure.
What is Exposure in Photography?
To begin down the path of mastering exposure in photography, let’s begin by quickly defining the term exposure.
It is simply the amount of light needed to create the image you want to create.
From this definition we learn that exposure is subjective. Some photographers may prefer more light, while others want a darker feel to their images. No matter what you prefer, learning to achieve that specific amount of light is imperative. And that is what this article is all about.
Components of Exposure in Photography.
You should now be familiar with the three components of exposure: aperture (f-stops), shutter speed and ISO. If you’re not familiar with any of those settings, or how they work, I have linked to in-depth articles on each. Stop now, and go have a refresher. If you feel comfortable with all three, keep reading.
These three components of exposure work together to give you the precise amount of light needed for the proper exposure of an image.
From here on out, we will assume you are working in manual mode. If you shoot in an auto mode, including aperture priority mode or shutter priority mode, adjusting one of the settings will not give you the results we are talking about below. I have a great article on shooting modes if you are interested in learning more about those as well.
It is critical to understand how these three work together to achieve the correct amount of light. Adjusting any one of the three will either add or remove light from your image.
Take a look at this image of our monkey friends.
You’ll notice right away that it is too dark, we need to add more light. So how do we fix it? We need to adjust one of the components of exposure to all more light to enter the camera. We can add more light by doing one of three things:
- adjusting the f-stop to make the aperture hole larger
- decreasing the shutter speed, which keeps the shutter curtain open longer
- increase the digital sensor’s sensitivity to light, requiring less light to create the exposure.
Any of these three options will work to add more light. However, each one of the three comes with a side-effect caused by the change.
By adjusting the aperture (f-stop) to add more light to the image, you’ll notice that our depth of field is increased as well.
However, there is a side effect to adding light through adjusting the aperture.
As the aperture hole gets larger to let more light in, you’ll notice that the image begins to have a more shallow depth of field.
If my image goal is to keep all of the monkeys sharp, then adjusting the aperture to add more light and brighten the image may not be the best solution.
By lowering the shutter speed to add more light to the image, you’ll notice that we start to get motion blur as well.
Adjusting Shutter Speed to add more Light.
If I add more light by slowing the shutter speed, or ‘dragging the shutter,’ as it is called, my image will definitely get brighter.
Slowing the shutter allows more light into the camera to expose the digital sensor. However, there is a side effect to adding light through shutter speed.
As the shutter slows to let more light in, you’ll notice that the monkeys begins to get motion blur (because the monkeys are swinging).
If my image goal is to keep all of the monkeys sharp, then dragging the shutter to add more light and brighten the image, may not be the best solution.
By increasing the ISO to add more light to the image, you’ll notice that the digital noise increases as well.
Adjusting ISO to add more Light.
If I add more light by increasing the ISO, my image will definitely get brighter.
Increasing the ISO, causes the camera’s digital sensor to be more sensitive to light, thus increasing the brightness of the image. However, there is a side effect to adding light through ISO.
As the sensitivity of the camera’s digital sensor increases, it also becomes more sensitive to other electrical signals, so you’ll notice that the image begins to show digital noise.
If my image goal is to keep the digital noise out of the picture, then increasing the ISO to add more light and brighten the image, may not be the best solution.
From my demonstration with the monkeys, you can easily see that there are choices that need to be made when you create an image. For our monkeys, to get the right amount of light, would we prefer to have:
- some monkeys out of focus (aperture)
- some monkeys blurry from swinging (shutter speed)
- the image having too much digital noise (ISO)
Imagine, if you will, this same scenario but instead of three monkeys there was only one. Aperture would be the go-to solution to increase the light, right?
This is because we would no longer be worried about the depth of field. As long as that one monkey was sharp, it would be a good image.
Same scenario but all three monkeys are again in the photo, but they are not swinging, they are stationary. Shutter speed would then be the go-to solution to increase the light. You understand why, right? As long as the monkeys are stationary (and I avoid camera shake), I can keep my aperture high enough to keep my depth of field large, and add light by slowing my shutter speed.
Each component of exposure: aperture, shutter speed, and ISO come with a side-effects that you must deal with and determine if it is the setting you want to adjust.
Understanding this is the first step to understanding exposure.
Let’s focus now on learning how to figure out the correct amount of light, or exposure for any particular image we plan to take.
How to Determine the Correct Exposure.
Amount of required light + image goals = exposure settings.
In this section we are going to go over this equation: amount of required light + image goals = exposure settings. Let’s start with the amount of required light.
Amount of required light.
Photography is the capture of light.
And to be a photographer, you need to begin to think like one, which means you need to constantly be considering the amount of light available and the amount of light required for photographs. When getting ready to take pictures, light should be your first consideration.
You should intuitively understand that more light is available at noon than at midnight. Simple to understand, right?
It makes sense then, that it is easier to take a photograph at midday rather than at midnight. The reason for this is because the amount of required light for a proper exposure is readily available to you at noon-day and unavailable to you at midnight. From this, we learn:
THE AMOUNT OF REQUIRED LIGHT FOR THE IMAGE DETERMINES OUR EXPOSURE NEEDS
Imagine, if you will, the amount of required light is an empty bucket. As a photographer, it’s your job to determine how to fill that bucket with light. We have three tools at our disposal to do this: f-stop, shutter speed, and ISO.
The size of the bucket we need to fill depends on the amount of available light, so there are several buckets one for each lighting scenario.
If we are shooting on a bright, sunny day at noon, the ‘required light bucket’ will be small. Bright, sunny days tend to create plenty of available light, and we only need a small portion of that light to get the correct exposure. Thus our ‘required light bucket’ is small.
If we are shooting indoors in the evening, the ‘required light bucket’ is large. Being indoors in the evening tends to restrict the amount available light, so we will need every bit of light we can get to create the proper exposure. Thus our ‘required light bucket’ is large.
It is important, that as a photographer, you learn to read the amount of available light with your eyes and use that info to know the amount of required light for a proper exposure. This is something you should constantly be practicing through your own real world experiences.
Amount of required light + image goals = exposure settings.
Determining Image Goals.
If you remember, we started this section by talking about the side-effects of each of the components of exposure. Besides light, aperture determines the depth of field, shutter speed controls motion or blur, and ISO manages digital noise. When creating an image, you need to decide which of these three so-called “side-effects”, is most important to the photograph you’re creating and adjust that setting FIRST!
WHAT’S YOUR GOAL?
If you are shooting portraits of people, then depth of field is your top priority. Creating or removing depth in portraits is of most importance. If you’re taking images of an individual, a shallow depth of field to create separation will be key (f2.8 or below).
If you are taking image of a group of people, you’ll need to be careful to make sure that all the individuals in the image are sharp. From the people in the front row, to the people in the back. Thus a large depth of field is your image goal (f5.6 or higher).
Each setting provides a certain amount of light to create the perfect exposure. The size of the cup represents the amount of light each setting gives. The larger the cup, the more light. The smaller, the less light.
If you are shooting a sporting event, dance recital, or any event with movement, shutter speed is your top priority. Either by obtaining motion blur to give the image a unique look (1/30th or below), or by avoiding motion blur to freeze your subject (1/125th or higher), motion becomes your image goal and shutter speed becomes your top priority.
Each setting provides a certain amount of light to create the perfect exposure. The size of the cup represents the amount of light each setting gives. The larger the cup, the more light. The smaller, the less light.
Image goals determines how you add light.
When you understand and determine what your image goals are, you are ready to start adding light based on those goals. The image below shows all three components of exposure and how adding light with that component will affect the image. Also, you can see how much light is added with each setting.
Remember! When creating an image, you must use light from all three columns of cups! You can not skip any of them.
Alright, let’s put it all together now…
First – to fill the ‘required light bucket’ you must choose wisely with your image goals in mind, and Second – there are tradeoffs. To get that large depth of field may require using a slower shutter speed which risks blurry pictures. Or, if you want to freeze motion in darker situations, it may mean losing some depth of field. Etc, etc.
You must fill the ‘required light bucket’ to the top every time you take a picture, and the choices you make are what makes you a photographer.
Required Light Buckets: The amount of light needed (based on available light) to achieve the correct exposure.
Image Goals: The goals you as the photographer have when creating images.
Mastering Exposure in the Real World.
Below are a few examples that can help you put together what was explained above. Use these real world examples to better understand how to master exposure in photography.
An Engagement Session
You are a portrait photographer who arrives at a park to take the engagement pictures of an awesome couple. It is a beautiful bright, sunny day and you are excited about creating some incredible images in this gorgeous park.
STEP ONE -DETERMINE LIGHT: It’s a bright sunny day, so you know that the required light for your images will be small. Take a look at the small bucket labeled ‘full sun’ to get an idea.
STEP TWO -DETERMINE GOALS: your primary goal with these images will be to achieve shallow depth of field; shallow enough to throw the background out of focus yet large enough to keep both of them tack-sharp.
SETTINGS: Knowing your bucket is small, if you shoot at f2.8 –a pretty large aperture hole, then you MUST have a fast shutter speed and a very low ISO. No trade-off’s here, a fast shutter speed to freeze motion and the lack of digital noise is exactly what you want.
A Ballet Performance
Your daughter has been practicing for years and her ballet performance is tonight. You are so excited to take some wonderful pictures of dancing that will be treasured forever. As you arrive and find your place to sit, you notice how dark the theater is. You begin to think about the settings you’ll need for your camera to get the shots you want.
STEP ONE -DETERMINE LIGHT: It’s a dark venue, so you know that the required light to create the exposure is large. Take a look at the large bucket labeled shooting indoors to get an idea.
STEP TWO -DETERMINE GOALS: your primary goal with these images to make sure your daughter is tack sharp. You know that she will be moving, so your shutter speed becomes your top priority.
SETTINGS: Keeping your daughter tack-sharp will require a shutter speed of no less than 1/125th of a second. The required light bucket is huge, and because 1/125th of a second doesn’t add that much light, you’ll need a ton of aperture and ISO. Set your aperture to f2.8, and your ISO to 6400 and you should be good to go.
Kids at the Park
You’re headed to the park with the kids for a picnic lunch, some relaxation while they play on the swings. It’s a beautiful day, warm but overcast. The clouds don’t look too dark for rain, but gives everything this gorgeous, soft light. You find your spot on the grass, spread out the blanket, and pull out your camera wanting to document the kids on the swings.
STEP ONE -DETERMINE LIGHT: It’s noon, but the sky is covered with clouds. Still plenty of light, but not like a bright sunny day. Take a look at the required light bucket labeled cloudy.
STEP TWO -DETERMINE GOALS: Those kids are going to be moving pretty quick on the swings, so your primary goal will be to make sure not to have any motion blur. A shutter speed of 1/500 should do the trick.
SETTINGS: The cloudy bucket isn’t huge, but with your shutter speed at 1/500th you’re going to need to get some light from somewhere else. We want some depth of field with our image, but not too much –f4 will give us great depth and a good amount of light. That leaves us needing a little more ISO than usual; 1600 ought to be perfect. Boom.
