What is Variable Depth of Field & How is it Achieved?

Using the depth of field to achieve the desired critical focus is an important concept. One newly aspiring filmmakers focus heavily on until they get it just right. When working with depth of field, the cinematographer must understand deep depth of field, shallow depth of field, and variable depth of field. But what is variable depth of field? And how does it impact the shot?

What is Depth of Field?

The depth of field represents the term that cinematographers use to describe the size of the area of an image in which objects appear sharp. When discussing depth of field, the area is known as the field, and the size of that area, is the depth of field.

It sounds complicated. But in simpler terms? Depth of field is essentially the width by height area. In which your objects appear sharp (and sometimes in focus) within the frame.

Depth of field is typically explained as either shallow depth of field, deep depth of field, or variable depth of field. The area involved in your depth of field can be manipulated through adjustments to your aperture, focus, and distance.

What is Variable Depth of Field?

In the past, filmmakers were forced to pick a depth of field and stick with it for the duration of a shot. However, variable depth of field, or the use of more than one depth of field within a shot, is not only possible.

It can be used to create visible blur or background blur effects that are sought after for various purposes.

Let’s take a look at how depth of field can vary:

• Shallow depth of field – represents  very short area in which, from front to back, your subject is in focus. The background is likely out of focus as is the foreground.
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• Large depth of field – represents a wider or longer area from front to back. In which your subject is in focus and clear. With much of the foreground and background in focus.

Adjustments

Variable depth of field is achieved when a cinematographer adjusts the aperture, focus, or distance of the camera to the subject. In order to manipulate the depth of field.

Such that, in a single shot, the subject is seen in both a shallow depth of field and a large depth of field. Or some combination of adjusting the depth of field to vary.

Why is Variable Depth of Field Used?

Variable depth of field may be used in films to communicate a shift in the subject’s mental health or emotional state.

Moreover, we see the transition from crisp, clear visibility in the background to a blurred, hard to see background. Often showcasing the subject’s shift in understanding representing a stark adjustment in emotions.

This shows the viewer that the background isn’t as important. As it may have originally been. While drawing focus on the extreme state of the character’s current situation or a pivotal moment in the narrative.