When you're first starting out shooting portraits, one of the most important decisions you can make is the focal length you shoot at, as it can vastly change the way a subject is rendered. This helpful video will show you how various focal lengths affect the look of a portrait to help you choose which one is most suitable for your work.
Coming to you from Pixel Viilage, this video will show you how a range of focal lengths from 14mm to 200mm affect the rendering of a subject's facial topography in a portrait. As you'll see, wide-angle lenses distort a subject's face in a way that's generally undesirable unless you're going for a specific artistic effect, while higher focal length telephoto lenses typically compress and flatten features to the point that you lose some of the unique topography of a person's face, which is why lenses between 85mm and 135mm are considered the classical portrait lengths for the balance they provide. Of course, that doesn't make them the "correct" focal length, so to speak; that's entirely an artistic decision, which is why it's important to have the ability to visualize how each focal length will render the face. Give the video above a watch to see the full range.