Understanding the focal plane in photography is essential in creating well composed photographs. The focal plane refers to the area of the image in which your subjects will be the most in focus. This area of focus spans from left to right - you can think of it as a horizontal line across the image. One can imagine taking a family portrait and having each person stand on the same line, filling up the scene from left to right. This line is within the focal plane of the image - everyone must stand on it to be in focus.
Another way to think about the focal plane is to think about the area of utmost importance in an image - where the eye will first be drawn to. This plane, despite the contradictory name, will not always necessarily be in focus. But within this plane of “accepted” focus will be focal POINTS, just like the line of focus in the group photo.
The focal plane is controlled by the photographer, and can be made wider or narrower by adjusting two main factors: depth of field and distance. Understanding how these work together will allow you to create focal planes specific to what you want to capture.
DEPTH OF FIELD
The focal area in an image can be controlled by the depth of field. Depth of field is referred to on the spectrum of deep vs. shallow. A deeper depth of field means: wider focal area + more in focus. A shallower depth of field means: a smaller focal area + less in focus. The depth of field can be controlled by adjusting the aperture on your camera lens. The aperture, also known as the f-stop, is the hole in the camera that opens and closes to let light in.
Deep depth of field + wider focal plane
For a deeper depth of field, and a wider focal range - a larger f-stop is needed. The bigger this number, the less light is allowed into the camera. This system is contradictory and actually works in reverse. So while f/16 and f/22 are big numbers, they mean that the aperture of the camera is contracting, letting in less light.
Images that have a deep depth of field will have a broader range of focal points. Landscape photography is a good example of where deep depth of field is used. A deep depth of field will allow the mountains of a landscape to be in focus, along with the surrounding trees and sky. These images therefore have a wider focal range.
Deep depth of field example. Phlow edit: Art 02 + Fade 02 + Medium Grain
Shallow depth of field + narrower focal plane
For a shallower depth of field and smaller focal range - a smaller f-stop is needed. The smaller the f-stop, the larger the aperture, the bigger the hole. The camera hole is opening, letting in more light. This creates images with a smaller focal range as only a thin portion of the image is focused, while the background is blurry. Portrait photos are good examples of where a shallow depth of field can be useful, utilizing a smaller focal range to concentrate on the person in the image.
Here's a simple guide to follow for expanding / contracting depth of field:
Deep depth of field = large f-stop (small aperture) + a slow shutter speed. Shallow depth of field = small f-stop (large aperture) + fast shutter speed.
Shallow depth of field + narrow focal plane example. Phlow edit: Moody 03 + Portrait 01 + Light Grain.
The second biggest factor in controlling the focal plane is distance. The things to consider and control are the distance between the subject and the camera AND the distance between the subject and the background.
- Distance between the subject and the camera. One can create a shallower depth of field - so a smaller focal plane by moving the camera closer to the subject, or area of focus. Create a deeper depth of field (a larger focal plane) by doing the opposite and moving the camera farther from the subject, creating more focal space.
- Distance between the subject and the background. One can create a shallower depth of field by moving the subject further away from the background. This will allow the focal plane to become smaller, blurring out the background and concentrating on the subject. Do the opposite to create a wider focal plane and deeper depth of field by moving the subject closer to the background. This extends the area of focus.
Small distance between subject + camera = shallower depth of field + narrower focal plane. Phlow edit: Moody 01 + Portrait 01 + Light Grain
Longer distance between subject + camera = deeper depth of field + wider focal plane. Phlow edit: Art 02 + Medium Heavy Grain
Depth of field and distance work hand in hand to affect the focal plane of an image. Understanding how to control the focal plane is important because you, as the photographer, can selectively draw viewers to certain points of an image. A portrait photographer may create a smaller focal plane to capture the detailed expressions in a smiling face, or a landscape photographer may create a wider focal plane to successfully photograph the expanse of a rocky mountain scene. Each is fundamental in successfully capturing your moment and story!