In today's Reel Rebel video production tip, Stephen Schweickart gives an overview of a depth of field, which is ultimately determines your focus area. Understanding and controlling the depth of field can be one of the most valuable tools to create more interesting, creative, and professional looking shots that appear to have more of a film look to them.
What is Depth of Field (DOF)?
Simply put, depth of field refers to the area of your scene that is in focus. As wikipedia states,
"Depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image."
It's important to first understand what it means to have a large depth of field (also called "deep focus") vs. a smaller depth of field (also called "shallow focus"). By creating a large depth of field, you will have an image where the entire image is in sharp focus. Most often, when using a standard camcorder in auto-focus mode, this is the effect that you will see. Conversely, shortening the depth of field (more easily achieved with a DSLR or camera with interchangeable lenses) will help you create an image where the main subject stands out more sharply and will be more in focus than the background or foreground. Using a DSLR camera gives you more control of depth of field.
Often times, using a more shallow depth of field will help you achieve a more professional, or cinematographic feel to your videos and this is what we're shooting for.
How to Achieve a Shallow Depth of Field
There are three things to keep in mind when managing your depth of field:
First, aperture refers to the opening in the lens that lets light into the camera and adjusting the aperture changes the brightness of the image being captured. When you let more light into the camera by opening up the aperture, you’re also drastically shortening the depth of field. When you're trying to make your focus more shallow, you'll want to open that aperture as far as it can go before you light your scene.
2) Focal length
Next is your focal length which refers to the distance from the optical center of the lens to the focal point. The higher the focal length, meaning the longer the lens is in millimeters, the shallower the depth of field will be and using a longer lens is one way to “crush the depth of field.”
3) Subject's distance from the camera
Just like using a longer lens, controlling the subject’s distance from the camera can affect the depth of field. By positioning your subject closer to the lens and keeping it in sharp focus, you'll get a shallower depth of field. As you roll the focus away from the lens the distance that is in focus deepens. So if your point of focus is two feet from the lens, you may only see two inches in focus around your subject, but if your point of focus is ten feet from the lens, much more of your scene will be sharp.
We hope this tutorial helps give you a better understanding of how you can use depth of field to produce more interesting shots that focus a viewer's eyes on the main subject while isolating it from its surroundings. Keep in mind that this is often a good look to go with when doing interview videos.
Question: When types of videos do you think are best suited for a more shallow depth of field look?