Focal length calculates the optical distance from the light source to the focal plane of the camera. In short, the focal length is a property of your camera lens that determines the angle of view and the magnification. Your camera has a few different lenses, like a zoom and prime lens, to name two. The zoom lens comes in when you are capturing landscapes or portraits. On the other hand, the prime lens has a larger maximum aperture that photographs the subjects even if there is some shaking or vibration from the photographer’s end.