Key Concepts:
* Perspective: How objects of different distances appear relative to each other. A wider perspective exaggerates the distance between objects, while a compressed perspective makes them seem closer together.
* Compression: How a lens appears to shorten the depth of field, making objects at different distances seem closer together. Longer focal lengths compress more.
* Distortion: Deviations from a realistic, objective representation. This isn't always negative, and can be used creatively.
How Focal Length Affects Facial Features:
* Wide-Angle Lenses (e.g., 18mm - 35mm):
* Exaggerated Perspective: Objects closer to the camera (like the nose) appear larger and more prominent, while objects further away (like the ears) appear smaller.
* Distortion: Can cause a "fish-eye" effect, especially at very wide angles. Features appear stretched and distorted, particularly towards the edges of the frame.
* Face Shape: Can make the face appear wider, rounder, or even bulbous.
* Best Used For: Environmental portraits where you want to capture a lot of the surrounding scene. Rarely used for flattering close-up portraits due to the distortion.
* Example: A nose might look disproportionately large, and the forehead might seem unusually wide.
* "Normal" Lenses (e.g., 50mm):
* More Natural Perspective: Mimics how the human eye sees. Distances are relatively accurate.
* Minimal Distortion: Provides a more realistic and balanced representation of facial features.
* Face Shape: Presents a face shape that is close to what you would see in person.
* Best Used For: General portraiture when you want a balanced and realistic look. A good starting point.
* Medium Telephoto Lenses (e.g., 85mm):
* Slight Compression: Flattens the image slightly, making the background appear closer.
* Flattering Perspective: Often considered ideal for portraits. Provides a good balance between realism and flattering compression.
* Face Shape: Generally elongates the face slightly and can make features appear more refined.
* Best Used For: Classic portraiture. Allows you to stand back a bit, making the subject feel more comfortable, and provides a nice out-of-focus background (bokeh).
* Telephoto Lenses (e.g., 100mm - 200mm+):
* Strong Compression: Greatly flattens the image, making the background appear very close and the subject stand out.
* Extreme Softening of Features: Can smooth out wrinkles and imperfections due to the flattened perspective.
* Face Shape: Elongates the face even more, which can be flattering if used carefully. However, over-compression can make the face look too flat or two-dimensional.
* Best Used For: Tight portraits, headshots, and when you need to isolate the subject from a busy background. Requires more distance between you and the subject.
* Example: The ears might appear closer to the face, and the overall shape might look narrower.
Factors to Consider When Choosing a Focal Length:
* Desired Look: What aesthetic are you trying to achieve? Do you want a natural look, a dramatic perspective, or a soft and flattering portrait?
* Environment: Are you shooting in a studio or on location? How much space do you have to work with?
* Subject's Face Shape: Some focal lengths are more flattering for certain face shapes.
* Distance: The farther you are from the subject, the more compressed the image will appear.
General Guidelines:
* Flattering Portraits: 85mm to 135mm are often considered the most flattering focal lengths for portraits.
* Natural-Looking Portraits: 50mm is a good starting point for a realistic representation.
* Environmental Portraits: 35mm or wider can be used to capture the surroundings.
* Avoid extremes: Very wide angles and extremely long telephoto lenses can be difficult to use well for portraiture, as they can introduce significant distortion.
In Summary:
Focal length is a powerful tool for shaping the way a face appears in a portrait. By understanding how different focal lengths affect perspective, compression, and distortion, you can choose the right lens to create the desired look and flatter your subject's features. Experimenting with different focal lengths is the best way to learn how they impact your portraiture and develop your own style.