Film is all about 'painting with light', so understanding these simple starting tips can really help your film look great.
1. Key light. Your first objective is to establish where your key light is coming from. The key light is the brightest light source. Outdoors this would be the sun. Inside it might be a window, or a 'practical' such as a desk lamp or candle. Once you have established the source of the key light you will then likely have to create it or possibly increase it for effect. In some cases you can completely invent the source of the key light such as when filming on a set. But you have to remember for continuity where it is, especially when shooting reversals or different angles.
2. Ambient or fill light. Once you have your key light sorted the next step is to create ambient light. For example, for an interior of someone standing by a window, the key light would be the sunlight coming in through the window. But you will also need some interior light to illuminate the other side of the person. The trick is to keep this as reduced as possible so that it does not fight with the key light. Often bouncing it off white card or a reflector can ensure it is a more natural fill light.
3. Rim or back light. To help separate a subject from the background a good device is to use rim or back light which can be achieved by placing a light directly behind (but obviously concealed) the subject with the light towards the camera but directed onto the subject. The effect is a line of light around the profile of the person that separates them from the background.
and back light are combined it can create
what is known as a '3 point light setup' which is
ideal but not always practical for every scene.
4. Colour temperature. You will notice that your lights probably came with blue and orange plastic sheets or 'gels'. This is to change the colour temperature of the lights. Light from the sun is blue (5600K or "daylight") while light from a standard bulb is orange (3200K or "tungsten"). The Arri fresnels we used are tungsten lamps so if we wanted to use them to create sunlight coming through a window for example we would then put the blue plastic gel over them. If you have a light that is daylight-balanced then you may need to use the orange gel to create tungsten for interior lighting.
5. Diffusion. Most lights cast a harsh light or create harsh shadows but if you need to soften it, especially if the light is falling onto someone's face, then you can use diffusion paper that likely came with the lights if you hired them.
6. Practicals. You can use practicals such as wall lights and desk lamps to help light a scene and make it realistic. If you need them to cast more light then check what bulbs they use and their wattage and see if you can safely change them for something brighter.
7. Reflector/bounce can help if you find your are running out of lights or the light is too harsh.
8. ND -neutral density sheets are good for reducing light, and not necessarily always from an actual light source. For example, a common problem is that sunlight coming through a window is too bright and becomes blown out, reducing everything else inside into darkness if you try to compensate for it with the camera. A solution is to put an ND on the outside of the window that brings the light level down to balance better with your interior lighting, rather than trying to match the exterior light levels inside.
9. Don't overlight a scene. It is sometimes better to use shadows to your advantage and this often means the placing of one or two simple lights in the right place, rather than trying to light the whole area.
Any other tips and corrections etc feel free to comment below.