Here's a breakdown of how different focal lengths affect the perceived shape of a face in portraits:
Shorter Focal Lengths (e.g., 24mm, 35mm, 50mm on a full-frame camera):
* Exaggeration and Distortion: Shorter focal lengths emphasize perspective. Things closer to the camera appear larger and things farther away appear smaller. This can lead to:
* Larger Noses: If the nose is closer to the camera than the ears, it will appear significantly larger, potentially dominating the face.
* Smaller Ears: Ears will appear smaller and pushed further back into the head.
* Wider Face: The overall face might appear wider and rounder.
* Curved Backgrounds: The background becomes more prominent and can exhibit more curvature, adding context but potentially competing for attention.
* More Environmental Context: Shorter focal lengths capture a wider field of view, incorporating more of the surrounding environment. This can be useful for environmental portraits, but it can also be distracting.
* Generally Less Flattering for Close-Up Portraits: While creative and useful for certain effects, short focal lengths are usually considered less flattering for close-up portraits of most people due to the distortion.
"Normal" Focal Lengths (e.g., 50mm on a full-frame camera):
* More Realistic Perspective: 50mm is often called the "normal" focal length because it approximates how we naturally see the world. The perspective distortion is minimized.
* Balanced Proportions: Features appear more in proportion to each other.
* Good General Purpose Lens: 50mm is a versatile focal length, suitable for a wide range of portrait styles, from headshots to half-body shots.
Longer Focal Lengths (e.g., 85mm, 100mm, 135mm, 200mm+ on a full-frame camera):
* Compression and Narrowing: Longer focal lengths compress the distance between objects in the scene. This leads to:
* Flattened Features: Facial features appear less exaggerated and more aligned on a single plane.
* Narrower Face: The face can appear slimmer and more angular.
* Reduced Nose Size: The nose appears smaller and less prominent.
* Brought Forward Ears: Ears appear larger and closer to the front of the face.
* Shallower Depth of Field: Longer lenses often have shallower depth of field, which can blur the background and draw more attention to the subject.
* Less Environmental Context: The field of view is narrower, so you capture less of the surrounding environment.
* Often Considered More Flattering: Longer focal lengths are generally considered more flattering for portraits because they minimize distortion and can make the subject appear more attractive.
* Require More Distance: To achieve the desired framing, you need to stand further away from your subject with a longer lens. This can sometimes make it harder to connect with them and direct them.
Here's a table summarizing the effects:
| Focal Length | Perspective | Face Shape | Nose Size | Ears | Depth of Field (typically) | Distance to Subject | Flattering? |
|---|---|---|---|---|---|---|---|
| Short (e.g., 24mm) | Exaggerated | Wider, Rounder | Larger | Smaller, Receded | Deeper | Close | Less, unless creative use |
| Normal (e.g., 50mm) | Realistic | Balanced | Normal | Normal | Moderate | Medium | Generally Good |
| Long (e.g., 85mm+) | Compressed | Narrower, Slimmer | Smaller | Larger, Closer | Shallower | Farther | Often More |
Important Considerations:
* Sensor Size/Crop Factor: These focal length guidelines apply to full-frame cameras. If you're using a camera with a smaller sensor (e.g., APS-C), you'll need to adjust the focal lengths accordingly. For example, a 50mm lens on an APS-C camera will have a field of view similar to an 80mm lens on a full-frame camera.
* Distance to Subject: The *distance* from the camera to the subject is just as important as the focal length. You can manipulate the apparent shape of the face by changing both the focal length and the distance. For example, if you use a wide-angle lens but move very far away, the distortion will be less noticeable.
* Posing: Good posing can minimize or even counteract the effects of focal length. Angling the face, tilting the head, and other posing techniques can greatly improve the look of a portrait regardless of the lens used.
* Personal Preference: Ultimately, the "best" focal length for a portrait is a matter of personal preference and the desired aesthetic. Experiment with different focal lengths and distances to see what you like best. There are no hard and fast rules.
* Lighting: Lighting plays a vital role in shaping the face. Be mindful of how different focal lengths and camera positions affect the lighting on the subject.
In conclusion, focal length changes the perceived shape of a face by altering perspective and compressing or exaggerating features. Longer focal lengths are generally considered more flattering for portraiture because they compress features and minimize distortion, while shorter focal lengths can create unique and creative effects but require careful handling to avoid unflattering distortion.