The Art of Portrait Photography
So you're interested in portrait photography, and you want to know what separates snapshots from art? Here are the things I consider vitally important:
Light is the single most important aspect of photography!
STOP right now, and read that back again and again until it sinks in. After all, the essence of the photographic art is the process of capturing light from the scene in order to create an artistic rendering. In a very real sense, photography is painting with light.
Long before photography and flashes were invented, classical painters posed their subjects next to large windows that acted like big soft boxes in order to create the right light to capture the mood they wanted to paint. Always pay attention to the light, and go to whatever lengths you need to (scheduling, rescheduling, adding light, etc...) in order to make sure you get the light right.
If you can't get great light, don't even bother clicking the shutter release -- your photo is just going to look like every other amateur with a point and shoot camera, otherwise.
You absolutely must have light to make a photograph, which is why it got top billing. It is absolutely the foundation of photography, but equally important is the subject. A strong subject is more than a good looking model. The setting, clothing, props, accessories, pose, and emotional expression all work together to tell a story. It's up to the photographer to make sure it's a story worth telling.
Focus isn't just about what to focus on, it's also about how much depth of field to show in the portrait. How much do you want to blur out background/foreground elements? How much of the subject really needs a sharp focus? With the right set of lenses, you can really have a lot of control over that aspect, and it makes a significant difference in the resulting images!
Also, don't discount the possibilities with regards to alternative points of focus. Generally, it's good to concentrate on eyes, but I often focus on lips, and sometimes create dramatic tension by having the primary subject out of focus, and instead focus on things like hands, or some object being held by the model. In one of my favorite shots, I focussed on a chess board with a very shallow depth of field, and lit up the subject's face so much that the highlights are all blown out.
For backgrounds, the general rule is to keep it simple. It is possible to do nice environmental portraits (and I have shot many), but it's very easy for backgrounds to clash and distract from the focus of your image. One thing to watch out for when you're just starting out is mergers -- background and foreground images have a tendency to seem to merge together in a photograph, so, for example, watch out that it doesn't look like trees are growing from the subject's head, and so on.
One key difference between an amateur shot, and a professional shot is composition. A great portrait photographer considers shapes, lines, framing, angles, negative space, where to place the point of focus in the frame for maximum impact, and so on.
Photographs are two dimensional, which makes it challenging to get a good sense of texture. The best way to play it up is to use strong shapes, composition, and light angles that compliment the textures in the scene.
If you're shooting for color, make sure that the colors compliment each other. If they don't, change up the wardrobe, the setting, etc... until they do. Painters don't choose random colors for their paintings. Why should photographers allow outside forces to dictate color choices?
Exposure isn't just about getting a proper exposure to record the scene. In especially high contrast scenes, for example, you have choices. You can get a proper exposure for shadows, or propper exposure for bright areas, but often, not both, and that can be a good thing. You can choose to take a high-key or low-key approach, and expose to emphasize certain areas of an image over others.
Keep in mind that you can use color, texture, and exposure to emphasize shapes in your compositions.
When you can coordinate all of these things, and get them working in harmony, that's when magic starts to happen. Like music, visual arts rely on harmony (shape, color, exposure), rhythm (texture), and plot elements to tell a story (setting, model).
Next time you point a camera at somebody, consider some of these ideas. Are you taking a snapshot, or creating art?