One of the most important things about being a photographer is taking control of your camera. The first step in this process is understanding and using the aperture and shutter speed of your camera. The aperture and shutter speed relationship is the basis of all photography. Once this relationship is understood, you can use that understanding to help you capture much better images.
There is a lot to digest in this post. You will probably have to come back to it it over time and that is perfectly normal.
First of all, what are aperture and shutter speed?
Aperture is the size of the hole (opening) in the lens that light travels though to hit your camera’s sensor.
Shutter speed is the amount of time light is allowed to hit the sensor in your camera. Aperture and shutter speed combine to capture an image.
Shutter speeds can range from thousandths of seconds (like 1/8000th of a second) to seconds (like 8″ seconds) or even minutes.
The aperture on a camera can be changed to be larger or smaller and therefore allow more or less light in to hit the camera’s sensor. If you have a larger opening that allows more light into the camera, you can use a faster shutter speed. If you select a smaller opening, that allows less light into the camera and will typically select a slower shutter speed.
One way to think about aperture and shutter speed is to imagine the amount of time it takes to fill a bucket with water using different size hoses. The bucket is your camera sensor, the hose is the aperture, and the amount of time it takes to fill the bucket is the shutter speed. A completely filled bucket is a correctly exposed image. If you have a very large hose (aperture), your bucket will not take a long time (shutter speed) to fill up. If you have a small, skinny hose (aperture), it will take a longer time (shutter speed) for your bucket to fill.
Apertures are represented by numbers and are always available to the photographer in your viewfinder or the camera’s display. Apertures are represented by the letter F followed by a number. So you might see F4 or F22 or even F6.3. I want you to pick up your camera now and turn it on. Try to find the aperture through the viewfinder and on the camera’s display. You may have to touch the shutter release button of your camera to wake it up and see these numbers.
Shutter speed and aperture are directly linked and affect each other. If you decide that you want to control the aperture and let the camera control the shutter speed, then you are using the camera in aperture priority mode. I use aperture priority mode 95% of the time.
In aperture priority mode, I select the aperture that I want and the camera will tell me what corresponding shutter speed will result in what it considers to be a correctly exposed image. I want you to start taking control of your camera by putting your camera in aperture priority mode. To put your camera in aperture mode, look for the mode button or the round scene button on your camera. It is usually on the top of the camera and easily accessible. If your camera has a rotatable round dial to control the camera’s mode, look for the A or the Av option and change your camera to that setting.
When you look at this diagram, the first part that may be confusing is that the smaller the number (like 2.8) the larger the opening. The larger the number (like 22) the smaller the opening. That seems counter-intuitive, and I could explain that it is because the numbers on the chart are actually fractions (hence the letter F to represent aperture) so F22 is actually 1/22 and therefore smaller than F4 which is actually 1/4. But that may just be too confusing. The important part to remember is that the larger the number, the smaller the hole (or opening or aperture).
Each step up the scale (for example from F4 to F5.6) allows half as much light into the camera. Each step down the scale (for example, F11 to F8) allows twice as much light into the camera.
So how does this relate to shutter speed? Let’s think about a scenario. In this scenario I am under cover on a slightly overcast day with the sun coming out from behind the clouds. When I select an aperture of F22, the camera selects a shutter speed of 1/60th of a second and I get a properly exposed photo. When I change my aperture to F2.8, I get a shutter speed of 1/4000 of a second. Both images are correctly exposed but there is a huge difference in the speed at which the image is captured. Back to our analogy of the hose and the bucket, the aperture of F2.8 is a wide hose and quickly fills our bucket with water while an aperture of F22 is a very thin hose and it will take longer to fill the bucket.
Most cameras allow you to select apertures between these numbers, so you may be see an aperture on your camera that is F4.5 or F5 or F7.1. This just means that you are able to change your aperture in one-third or half steps (also known as stops).
If you select an aperture that is not a full step up or down the scale, the shutter speed will also reflect this change. In the example above, if I had selected a shutter speed of F6.3, the camera would have selected a shutter speed of 1/800 of a second. If I had selected F7.1, then the camera would have given me a shutter speed of 1/640. Remember that these examples are for the image that I was capturing. As soon as I turn my camera in another direction, all of the shutter speed for my selected apertures will change.
Workshop: Aperture and Shutter Speed
Change your camera into aperture mode. This is usually represented by an “A” or “Av” in many cameras. In aperture mode, you select the aperture (size of the opening in the lens) and the camera will select the shutter speed (amount of time the light is allowed to hit your sensor). Now lightly press the shutter release button and take a look at what aperture and shutter speed you see you are getting for your current situation. Remember if you are inside or somewhere dark, you may get very slow shutter speeds.
Next change your aperture (usually achieved by rotating one of your command dials on your camera) and take note of how the change in aperture affects the shutter speed. Change the aperture to F8 and look at the shutter speed (for example, 1/250). Next, without moving your camera, change the aperture to F11 (making the hole in the lens smaller). The shutter speed should be half of what it was at F8 (for example, 1/125). Now without moving the camera, change the aperture to F5.6 and the shutter speed should be twice as fast as it originally was (for example, 1/500). Take some time to explore this with your camera as it is very important to understand.
You may also see numbers like 2″ which means 2 seconds or 0.3″ which means 1/3 of a second. These are very slow shutter speeds and will result in blurry pictures unless your camera is on a tripod. Remember, when you change the aperture, you are changing the size of the opening that allows light to come in the camera and the camera will decide what the corresponding shutter speed should be to create a correctly exposed image. Back to our hose and bucket example, I am deciding what size hose to use and someone else (the camera) will tell me how long it will take to fill my bucket.
What you need
A camera with a lens that you can change the aperture.
Remember
Aperture and shutter speed are directly linked.
Put your camera in aperture priority mode.
Observe how the changing the aperture directly affects the shutter speed.
