1. Perspective and Compression:
* Wide-Angle Lenses (e.g., 24mm, 35mm):
* Exaggerated Perspective: Objects closer to the camera appear larger and objects further away appear smaller.
* Expansion: Noses and foreheads can appear larger and more prominent, while ears can appear smaller and further back. This leads to distortion and often an unflattering representation of facial features.
* Subjectively "Wider" Face: The face appears broader than it actually is.
* Use Cases (rare for portraits): Can be used for environmental portraits where you want to emphasize the subject's surroundings.
* "Normal" Lenses (e.g., 50mm):
* More "Natural" Perspective: Mimics how our eyes perceive the world at a similar viewing distance.
* Minimal Distortion: Faces appear more true to their actual proportions.
* Good starting point: Often used as a versatile lens, can be used for full body, half body, and headshots.
* Telephoto Lenses (e.g., 85mm, 100mm, 135mm, 200mm):
* Compression: Objects at different distances appear closer together.
* Flattering Effect: Facial features are flattened slightly, making the face appear slimmer and more balanced. Noses appear smaller, and the overall shape becomes more streamlined.
* Shallow Depth of Field: Excellent for blurring backgrounds and isolating the subject.
* Subjectively "Slimmer" Face: The face appears narrower and more defined.
2. Subject Distance and Framing:
* To achieve the same head size in the frame, you need to stand closer to your subject with a wide-angle lens and further away with a telephoto lens. This distance directly influences the perceived distortion.
* Close Distance (Wide-Angle): Exaggerates perspective and features.
* Further Distance (Telephoto): Compresses perspective and features.
3. Key Effects Summary:
| Focal Length | Perspective | Compression | Subject Distance | Face Shape Effect | Common Usage |
|---|---|---|---|---|---|
| Wide-Angle (e.g., 24mm-35mm) | Exaggerated | Minimal | Close | Wider, distorted, large nose | Environmental portraits (use with caution on headshots) |
| "Normal" (e.g., 50mm) | Relatively Natural | Moderate | Medium | More accurate, minimal distortion | Versatile, good starting point |
| Short Telephoto (e.g., 85mm) | Moderate | Moderate | Further | Slightly slimmer, flattering | Popular portrait lens |
| Medium Telephoto (e.g., 100mm-135mm) | Significant | Significant | Farther | Slimmer, more defined features | Classic portrait lens, great for shallow depth of field |
| Long Telephoto (e.g., 200mm+) | Extreme | Extreme | Very Far | Very slim, flattened features | Professional portraits, studio work |
Practical Considerations for Choosing a Focal Length:
* 85mm to 135mm lenses are generally considered ideal for portraiture because they offer a flattering balance of compression and shallow depth of field without extreme distortion.
* Consider the subject's face shape. If someone has a round face, a telephoto lens can be more flattering. If someone has a very narrow face, a slightly wider lens might add some dimension.
* Think about the background. A wide-angle lens will capture more of the background, which can be desirable for environmental portraits. A telephoto lens will blur the background, drawing more attention to the subject.
* Your working space matters. If you're shooting in a small studio, a shorter focal length might be necessary to get the framing you want. If you're shooting outdoors, you'll have more room to work with longer lenses.
In conclusion:
Focal length is a powerful tool for shaping the perceived form of a face in portraiture. Understanding how perspective and compression work will allow you to choose the right lens to create the most flattering and expressive images of your subjects. Experiment with different focal lengths to see how they affect the final result and develop your own preferred style.