Movie Making How To: What Is Depth of Field is a short three-minute video that answers the questions: what is depth of field and how it’s used in cinematography?
Movie Making How To: What Is Depth of Field? Transcript:
Depth of field is something that all filmmakers should be aware of. It’s the area of the shot that’s going to be in focus and it’s effected by several choices: the lenses, the lighting and the blocking.
First, what is depth of field? It is the area of your shot that is in focus. Now in truth there is only one area of the shot that is in focus. Depth of field is broken into thirds. If you have 9ft in your depth of field, it will be 3ft infront of the subject, and 6ft behind. An object immediately behind the subject will be in focus, but anything in the background won’t be.
What are the different factors that affect depth of field? Your lens choice and the focal length are going to effect depth of field greatly. A long lens has less depth of field that a wide-angle lens like the one that we’re using now. That’s because we’re using a wider angle of view.
All lenses have an aperture which open and close to give exposure to your image. It’s a backwards world where the smaller the numbers the bigger the opening and the larger the number the smaller the opening. It’s really an inverse thing: 16 over 1 or 2 over 1. When it (the armature) is wide open the light is scattered and it’s harder to focus it down on your film plane or sensor. However, if you narrow it down, it’s a lot easier to get things in focus and create a depth of field.
Another factor is light level. The more light you have, the more depth of field you’ll have. In low light level you’re going to have less depth of field because, as before, you’re going to have to open up the aperture of the camera and your depth of field will plummet. So if you want less depth of field, you drop the light level which can be done by either taking away lights or adding a Neutral Density Filter to your camera which lessens the light.
The final factor that affects depth of field is the size of your imaging sensor or film feed. The bigger the sensor or gate, the harder it is to focus the light.
Depth of field is an incredibly powerful tool in enabling the audience to focus on what it is that you want them to see. So use it to tell the stories that you want to tell.
Movie Making How To: What Is Depth of Field? Credits:
Framelines has been nominated for an Emmy and is an award-winning series that was broadcast on PBS.