Short Notes on Key Electronic Media Concepts
a. Depth of Field (DOF)
Depth of Field refers to the range in a photograph or video that appears acceptably sharp and in focus. It is the distance between the nearest and farthest objects in a frame that appear clear. DOF can be shallow or deep depending on camera settings and creative intent.
A shallow depth of field results in a blurry background and sharp focus on the subject, often used in portrait photography and cinematic shots to draw attention. A deep depth of field keeps everything in focus—from foreground to background—and is used in landscapes or wide shots.
Factors influencing DOF include:
- Aperture: A wider aperture (lower f-number like f/2.8) gives shallow DOF; a narrow aperture (f/16) increases DOF.
- Focal Length: Telephoto lenses reduce DOF; wide-angle lenses increase it.
- Distance to Subject: The closer the camera is to the subject, the shallower the DOF.
Depth of Field is a vital storytelling tool in filmmaking and photography, helping guide viewer attention and set the visual tone.
b. Exposure Triangle
The Exposure Triangle consists of three camera settings—Aperture, Shutter Speed, and ISO—that work together to determine the exposure of an image or video. Mastering the exposure triangle is essential for photographers and videographers to capture well-lit and balanced shots.
- Aperture: Controls the size of the lens opening. Affects brightness and Depth of Field. A wide aperture (f/1.8) allows more light; a narrow aperture (f/16) allows less.
- Shutter Speed: Determines how long the camera sensor is exposed to light. Faster speeds (1/1000s) freeze motion; slower speeds (1/30s) allow blur and more light.
- ISO: Controls the sensor’s sensitivity to light. Low ISO (100) gives clean images; high ISO (3200+) is good in low light but adds noise.
Balancing these three elements allows creative control over exposure, motion blur, and image clarity. For example, in low light, increasing ISO and using a wide aperture can help maintain correct exposure. The triangle is foundational in both still and motion picture production.