Photo composition refers to how your subject fills the frame. Focal length determines the field of view: a 50mm lens on a full-frame camera captures a wider scene than a 200mm lens at the same distance. Longer focal lengths compress perspective and are preferred for portraits to avoid distortion.
Crop factor is the ratio between a camera sensor and a full-frame (35mm) sensor. An APS-C sensor (crop factor 1.5-1.6) makes a 50mm lens behave like a 75-80mm lens in terms of field of view. This calculator converts your actual focal length to the equivalent full-frame focal length.
For headshots, use 1.5-3 meters with an 85-135mm equivalent lens. For half-body portraits, 3-5 meters works well. Full-body shots typically require 5-10 meters. This calculator shows exactly how your subject will fill the frame at any distance.
Higher megapixels provide more detail for cropping. A 24MP camera at 5m distance with an 85mm lens captures a face at roughly 600 pixels height. For professional retouching, aim for at least 1000 pixels across the face.
