Shorter Focal Lengths (e.g., 24mm, 35mm):
* Wider Perspective: These lenses capture a broader field of view, including more of the background.
* Facial Feature Distortion: Close-up portraits with wide-angle lenses can lead to significant distortion.
* Exaggeration: Features closest to the lens, like the nose, appear larger and more prominent. Features farther away recede into the background.
* Rounded Features: The face can appear rounder or wider than it actually is.
* Elongated Features: Features can appear elongated toward the edges of the frame.
* Sense of Depth: The distance between objects in the image appears greater, creating a stronger sense of depth.
* Ideal for:
* Environmental portraits where you want to show the subject within their surroundings.
* Creative portraits with a distorted, artistic effect.
* Group portraits where you need to fit everyone into the frame while still being relatively close.
"Normal" Focal Lengths (e.g., 50mm):
* Closest to Human Vision: 50mm on a full-frame camera (or equivalent on crop sensors) is often considered a "normal" focal length because it provides a perspective similar to how the human eye perceives the world.
* Minimal Distortion: There is relatively little distortion of facial features. Proportions generally appear accurate.
* Balanced Perspective: Offers a good balance between including background and focusing on the subject.
* Ideal for:
* General-purpose portraiture.
* Documentary-style portraits.
* Any portrait where you want a natural, realistic depiction of the subject.
Longer Focal Lengths (e.g., 85mm, 100mm, 135mm, 200mm+):
* Compressed Perspective: These lenses compress the distance between objects, making the background appear closer to the subject.
* Flattering Facial Features:
* Slimming Effect: The face appears narrower and more streamlined.
* Smoother Skin: The increased distance allows for more even lighting and can help to smooth out skin imperfections (especially when combined with a shallow depth of field).
* Reduced Nose Prominence: The nose appears less prominent compared to wide-angle lenses.
* Shallow Depth of Field: Longer focal lengths, especially when used with a wide aperture, create a shallow depth of field, which blurs the background and isolates the subject.
* Increased Distance: You need to stand farther away from your subject to get the same framing.
* Ideal for:
* Classic portraits where a flattering and aesthetically pleasing depiction of the subject is desired.
* Portraits that emphasize the subject and minimize distractions in the background.
* Candid portraits taken from a distance, allowing the subject to be more relaxed.
* Portraits where you want to create a soft, blurred background ("bokeh").
Key Considerations:
* Sensor Size: The impact of focal length is also affected by the sensor size of your camera. A 50mm lens on a full-frame camera will have a different field of view and perspective than a 50mm lens on a crop-sensor camera (e.g., APS-C). You need to consider the "equivalent focal length" when comparing lenses across different sensor sizes.
* Distance to Subject: The distance you stand from the subject is directly related to the focal length you use. To maintain the same framing, you'll need to move further away when using a longer lens and closer when using a wider lens. This distance greatly influences perspective.
* Aperture: The aperture you choose (e.g., f/1.8, f/5.6) controls the depth of field (the area in focus). A wider aperture (smaller f-number) creates a shallower depth of field, blurring the background. This is often used in portraiture to isolate the subject.
In Summary:
The "best" focal length for portraiture depends on the desired effect. Understanding how focal length affects perspective and facial features allows you to choose the right lens to achieve your artistic vision. Experiment with different focal lengths to see what works best for you and your subjects. Many photographers find that 85mm to 135mm lenses are a good starting point for flattering portraits.