BASIC EQUIPMENT YOU’LL NEED
You can do photography with even the simplest of cameras, but the principles that I’d like to teach are for people who want to learn to use a DSLR camera, a micro four-thirds camera, or at least a camera that allows the photographer to adjust the shutter speed, aperture, and ISO. Even some pocket cameras have this functionality.
Now that you have your camera, it is time to learn exposure.
EXPOSURE–THE MOST BASIC ELEMENT OF PHOTOGRAPHY
When photographers talk about “exposure,” we simply mean the brightness or darkness of a photo. It seems simple enough to take a photo that is correctly exposed (has the proper brightness or darkness), but in reality it can be quite the trick.
To help get the right exposure with your camera settings – you can download this Camera Expsure Cheet Sheet guide.
If you’re reading this article, it probably means that you currently shoot on the “Green mode” of your camera–or the automatic setting. That means the camera entirely controls the exposure of the picture. When you shoot on automatic mode, your camera selects an aperture setting, an ISO setting, a shutter speed, and a host of other settings for you.
Automatic can be handy, but it also seriously limits your creative ability to make a beautiful picture.
Want proof that automatic isn’t the best way to shoot? Check out the picture below. On the left, the picture was taken entirely in automatic mode on a Canon Rebel DSLR. That might look okay to you… until you see the picture on the right. Same sunset. Same camera. The pictures were taken only seconds apart. The difference? The picture on the right was taken using manual exposure.
Which photo do you prefer? Probably the picture on the right! By choosing a creatively dark exposure, the rich colors in the sunset were allowed to shine through.
However, technically, the photo on the left is “correct,” and the photo on the right is “incorrect.” The camera saw through the lens and tried to expose the bird so that it wouldn’t become a shadow. To me, the photo was not about exposing the bird properly, but exposing the sunset properly. The bird was just a nice shape to include in the foreground. This is exactly why you must learn exposure–because sometimes the “scientifically correct” exposure is not the best exposure to make the photo look how you want it to.
Now that you understand why it is so important to take control over the exposure, let’s move on to exposure triangle – shutter, aperture and ISO. which are the tools you need to control the exposure.
From the example of the sunset picture, you have learned the importance of taking full control over the exposure on your camera. Now, it’s time to dig into your camera and learn the three most basic tools available to you in controlling the exposure.
Those tools are shutter speed, aperture, and ISO. After I explain what each one does, I’ll explain why we need three separate tools to control the brightness or darkness of the photo.
The aperture is a small set of blades in the lens that controls how much light will enter the camera. The blades create a octagonal shape that can be widened (we photogs call it shooting “wide open”), or closed down to a small hole. Obviously, if you shoot with the aperture wide open, then more light is allowed into the camera than if the aperture is closed down to only allow a tiny hole of light to enter the camera.
So suppose you take a picture that is too bright. How do you fix it? Simply choose a smaller aperture. Aperture sizes are measured by f-stops. A high f-stop like f-22 means that the aperture hole is quite small, and a low f-stop like f/3.5 means that the aperture is wide open.
Let’s test your knowledge to make sure you have it down. If you take a picture and it’s too dark at f/5.6, would you choose a lower f-stop number or a higher one? Yep! You’d choose a lower f-stop number, which opens up the aperture to let in more light. The size of the aperture controls more than the brightness or darkness of the picture, though.
The aperture also controls the depth-of-field. Depth-of-field is how much of the picture is sharp, and how much is blurry. If you want to take a picture of a person and have the background be blurry, you’d use shallow depth of field. If you want to take a picture of a sweeping mountain vista, you’d want to use a small aperture size (high f-stop number) so that the entire scene is in sharp focus. If you, like me, are more of a visual learner, then I think this graphic will help solidify the information about aperture. Take a minute and make sure you understand this info before moving on.
The shutter is a small “curtain” in the camera that quickly rolls over the image sensor (the digital version of film) and allows light to shine onto the imaging sensor for a fraction of a second. The longer the shutter allows light to shine onto the image sensor, the brighter the picture since more light is gathered. A darker picture is produced when the shutter moves very quickly and only allows light to touch the imaging sensor for a tiny fraction of a second. The duration that the shutter allows light onto the image sensor is called the shutter speed, and is measured in fractions of a second. So a shuttedr speed of 1/2 of a second will allow more light to touch the image sensor and will produce a brighter picture than a shutter speed of 1/200 of a second. So if you’re taking a picture an it is too dark, you could use a slower shutter speed to allow the camera to gather more light.
Just as the aperture affects the exposure as well as the depth-of field, the shutter affects more than just the exposure. The shutter speed is also principally responsible for controlling the amount of blur in a picture. If you think about it, it makes sense that the shutter speed controls how much blur is in the picture.
Imagine a man sitting here at computer desk waving to you (you don’t have to imagine very hard if you just look at the picture above). If you take a picture of man with a shutter speed of 1/30th of a second, then his hand will have moved in the time that the camera is recording the picture. To get rid of the blur, you need to increase the shutter speed to around 1/320th of a second. At this speed, his hand is still moving, but the camera takes the picture so fast that my hand travels only such a small distance that it is not noticeable in the picture.
The funny thing about ISO is that it is an acronym, but nobody really knows what it stands for. It is always just called ISO even though it really stands for International Organization for Standardization. Every once in a while, you’ll hear an older photographer pronounce it “I-so”, but almost everyone pronounces it “I.S.O.” The ISO controls the exposure by using software in the camera to make it extra sensitive to light.
A high ISO such as ISO 1,600 will produce a brighter picture than a lower ISO such as ISO 100. The drawback to increasing the ISO is that it makes the picture noisier. Digital noise is apparent when a photo looks grainy. Have you ever taken a picture at night with your cell phone or your pocket camera, and noticed that it looks really grainy? That is because the camera tried to compensate for the dark scene by choosing a high ISO, which causes more grain.
What constitutes a “high” ISO is constantly changing. Camera companies are constantly improving the ability of cameras to use high ISOs without as much grain. A few years ago, only the highest-end pro DSLR cameras could achieve 2,000 ISO, and now even entry-level DSLR cameras can shoot at this level. Since each camera is different, you would do well to do a few tests with your camera to see how high of an ISO you can shoot at without making the image overly grainy.
PUTTING IT ALL TOGETHER
I know exactly what you’re thinking: “Why do I need three tools to control the exposure!?!? Wouldn’t one suffice?” The answer is no, and I’ll explain why with an example. In January 2012, Jim Harmer took a trip to his favorite place on the planet to take pictures–Yellowstone National Park. His guide informed them that the bighorn sheep in the park were dying off very quickly due to whooping cough, so He worked hard that week to capture pictures of the last few sheep in that area of the park. Around 9AM on a cloudy day, He found a small group of bighorn sheep and started photographing them with a long 600mm lens. The early hour and clouded sky made the situation quite dark for shooting.
The lens he was working with had a maximum aperture size of f/4. So He set his aperture at f/4 to gather as much light as possible. This also impacted the depth-of field to blur out the rocks behind the bighorn sheep. Next, He set his shutter speed. He wanted to capture action in the photo, so He set his camera to 1/1000th of a second shutter speed. He knew that this fast of a shutter speed would prevent any motion blur from the sheep running on the mountain side. Then, He took a picture. WAAAY too dark! He couldn’t compromise his shutter speed or aperture, so He knew they needed to use the third player in the exposure triangle–the ISO.
He played around with his ISO and found that if he increased it to ISO 640, it made the picture bright enough to take the picture without making it overly grainy. Yahtzee! This combination of shutter speed, aperture, and ISO worked out perfectly. Now can you see why you need to know how to shutter, aperture, AND ISO, and know how to set them independently on your camera.