Here's a breakdown:
1. Wide-Angle Lenses (Short Focal Lengths - e.g., 14mm - 35mm):
* Exaggerated Perspective: Objects closer to the camera appear significantly larger, while those further away appear smaller. This is the key to understanding the distortion.
* Elongated Faces: The nose and other features closest to the camera can appear disproportionately large, stretching the face and making it look longer.
* Receding Background: The background appears to stretch away quickly, emphasizing the distance.
* Generally Unflattering for Portraits: Unless used creatively or intentionally for a dramatic effect, wide-angle lenses are generally avoided for close-up portraits because they can make subjects look distorted and unflattering.
* Best Used For: Environmental portraits, where you want to show the subject in a wider context and don't mind some distortion.
2. Standard Lenses (Around 50mm):
* More Natural Perspective: Offers a perspective close to what the human eye sees. Distortion is minimized.
* Relatively Accurate Representation: Facial features appear more proportional and true to life.
* Versatile: Good for a variety of portrait types.
* Common Choice: A 50mm lens is often a good starting point for learning portraiture, offering a balance between natural perspective and a manageable working distance.
3. Telephoto Lenses (Long Focal Lengths - e.g., 85mm, 105mm, 135mm, 200mm+):
* Compressed Perspective: Compresses the distance between objects, making them appear closer together.
* Flattering for Faces: The compression effect tends to slim the face, smooth out wrinkles, and make the eyes appear more prominent.
* Rounded Appearance: The facial features appear more rounded and less angular.
* Blurred Backgrounds (Bokeh): Longer focal lengths, especially when paired with wide apertures (low f-numbers), create a shallow depth of field, resulting in beautifully blurred backgrounds (bokeh) that isolate the subject.
* Ideal for Portraits: Often considered the most flattering focal lengths for portraits because they minimize distortion and create pleasing compositions.
* Requires More Distance: You need to stand further away from your subject to achieve the desired framing.
* Different 'Look': 70-200 lenses offer a more "professional" or "high-end" feel to many casual observers.
Here's a table summarizing the effects:
| Focal Length | Perspective | Facial Feature Distortion | Background | Ideal For |
|--------------|-------------------|-----------------------------|---------------------|-------------------|
| Wide-Angle | Exaggerated | Elongated, Enlarged | Stretched, Receding | Environmental Portraits (use with caution on close-ups) |
| Standard | Natural | Minimal | Relatively Neutral | Versatile Portraits |
| Telephoto | Compressed | Rounded, Slimmed | Blurred (Bokeh) | Flattering Portraits, Close-ups |
Key Considerations:
* Distance Matters: The distance between the camera and the subject also plays a crucial role in perspective. Even with a telephoto lens, if you're very close to the subject, you'll still introduce some distortion.
* Crop Sensor vs. Full Frame: The "effective" focal length changes depending on your camera's sensor size. A 50mm lens on a crop sensor camera (e.g., APS-C) will have a narrower field of view and behave more like a ~75mm lens in terms of perspective. You need to consider the crop factor when selecting lenses.
* Aperture: While not directly related to focal length distortion, aperture (f-stop) significantly impacts the depth of field (how much of the image is in focus). Longer focal lengths with wide apertures create shallow depth of field, blurring the background and further isolating the subject.
* Personal Preference: Ultimately, the best focal length for a portrait depends on the desired look and the subject's features. Experiment to find what works best for you and your style.
In conclusion, choosing the right focal length is a key artistic decision in portraiture. Understanding how it affects perspective and facial feature distortion allows you to create portraits that are both technically sound and aesthetically pleasing.