How to Control Light with F-Stop
Let There Be Light!
The term “f-stop” might sound scary if you never heard of it, but the concept behind this term is quite simple. It represents the amount of light that enters the camera lens and by controlling the amount of light, you control how dark or light the photo will be, as well as how much you want to blur the background.
You see? That was not hard at all and you already gained some insight into how professionals do their magic! So now let’s move on to the details.
How to Control F-Stop
Inside the lens is a movable opening, which is called the aperture. The aperture can be opened up a lot or a little, and the more the aperture is open, the more light will be allowed to come in, and vice-versa. You have complete control of this! How you ask? Here’s how: There is a setting on your camera that controls the amount of light you want to let in, and that setting is called f-stop, officially called “focal stop”. Most lens apertures are set in increments as follows: 2.8, 3.5, 4.5, 8, 11, 16, and some lenses (the more expensive ones) also have a setting of 1/8.
What Do the F-Stop Numbers Represent?
This number is a representation of the size of the opening; in other words, it relates to the size of the hole inside the lens through which light travels. A larger f-stop number means that the aperture is smaller (let’s less light in), while a smaller f-stop number means that the aperture is larger (let’s more light in).
The relationship between these two factors is logarithmic, which means that changing the F-Stop one increment, either way, will change the aperture by a factor of two. For example, if a photographer were to set the aperture to f/8 and then change it to f/16, the amount of light coming through the lens would be cut in half (smaller hole). Alternatively, if the photographer would double the amount of light coming through the lens, he or she would set the aperture to f/4.
How to Change the F-Stop?
You can change the f-stop by adjusting the aperture. On today’s digital cameras, the setting for the f-stop is displayed on the camera’s LCD screen and you can control it by adjusting the AV setting on the camera.
When to Use Which F-Stop
You can get different types of effects depending on which f-stop setting you use. Let’s take a look at how this works.
Portraits and Macro Photos
Backgrounds can be distracting for portrait photography, so your goal would be that you would want to draw attention to the main subject by blurring out the background. In so doing, you would use aperture settings of f/2.8 or f/1.8 (if your lens has this setting). The lower the number, the more blurred the background will be.
The term for making more of the background blurry is called shallow depth of field. This provides the image behind the subject to have a hazy or “foggy” look and results in drawing the viewer’s attention to the primary subject (not the background).
You might be asking yourself “If I open the aperture more and let more light in, won’t the image be too bright?” The answer is yes, but you can also control the amount of light entering the lens by using the shutter speed setting. We’ll discuss how to do this in another article.
Night Photography
For photos of night photography, the same applies. You would use a small f-stop number for a more open aperture so additional light can come into the lens. 2.8 or lower is what should be used. By using these low f-stop settings, you can expose the picture in less time.
Landscape and Architecture
In these scenarios, you want the f-stop to keep everything sharp and in focus.
Conclusion
You can control how much light can enter the camera and it is called f-stop. It is a useful metric for creating a shallow depth of field. Knowing how to use the f-stop will improve your photography skills greatly.