A quick introduction Being from a theatrical background I quickly rolled into the technical side of shows and events. Now, I work mostly as a lighting technician for live events. I have also worked on a number of professional recordings, for film, TV and projection, so I'm not specialized in that side of the industry but have managed to pick up quite a few tricks and techniques used. I'm going give you an introduction for lighting in general, but one that is also very much usable for video pieces. Rule 1 You cannot see light itself, you can only see the effect it has on objects. Light itself is invisible. It sounds obvious, but it helps to focus on the object and not too much on the light itself. Always be thinking about the surface of the object and how it is going to react to the light source. The human eye So following rule 1, the most important factor in lighting is how we see its reaction. Therefore the most important tool is our eyes. Light waves are measured on a spectrum of nanometres, the nanometres being the measurement of width of the light wave. The visible spectrum is from 400nm to 700nm, 400nm being in the region of ultraviolet and 700nm being around infrared, two words you've definetly come across before. All the colours that we see occur in-between these two extremes. The human eye, basically, has three different types of sensors, one for red, one for green and one for blue. You can extract white into equal parts of red, green and blue (RGB). Equally if you have three different light sources of red, green and blue you can create white. People who are "colour blind" are people with deficiencies of the different light sensors. Roughly these sensors react differently to light wave sizes, wiggle little and send info to your brain. Your brain combines the three channels to create an end result. I've just murdered a science and insulted anyone who actually knows anything about it, but in a nutshell that’s "more or less" how it works. Colour ...is a huge topic that I'm not going to go into any detail at all, but lets talk alittle about the colour temperature of the light source - not to be confused with its heat. You have white light. Just a blank light source, no shades or colour filters. A regular light bulb, a candle, the sun, each of which could be described as white light, but the actual colours are very different. Hotter light sources have a bluer and colder colour and lower temperature sources have a more red but seemingly warmer colour. I know it sounds stange, the higher the colour temp the "colder" the light seems, but you can think of it as a piece of metal thats firstly glowing red: Nice and hot, but with a warm colour. Now, heat that piece of metal further and eventually it'll glow white hot. A lot hotter, but a much "colder", harsher colour. This is an important issue when recording film. The sun has a very high colour temperature in comparison to a lightbulb or halogen light. The sun is a significantly more blue colour. The human eye adapts somewhat to the current light source, but it's much more visible on screen when recording. You'll notice on your own videos that when you record inside at night time, even if there is enough light it still comes out quite red. A very rough scale of colour temperatures: RED candle - regular bulb - halogen light - TL (or other gas based light source) - sun BLUE If you want to combine inside shots and outside shots you're going to have to do some correcting at some end of the process. As a rule, the less computer correction (messing around with the colours in what ever program you're using for editing) the better. Digital correction always reduces the quality of the recording, no matter what you do: If you change information, you reduce detail. But you can manipulate the colour temperature of a light source with the use of filters, changing the colour temperature but not the output of the source. For a better result you can start setting up a light scenario your self, creating the situation you want. For this you'll need resources, as household fittings just won't cut it. You'll need more heavy duty material... Light colour filters (gels) Filter is the buzzword, and it's not just a bit of plastic you put in front of the source, it's what that piece of plastic does and doesn’t let through. White light is RGB red, green, blah. So a "red" colour filter is a piece of plastic that filters out green and blue light allowing only red light to pass through. Ironically a "red" colour filter is actually an "everything but red" colour filter. Similarly, a blue filter extracts green and red from white. A clear plastic filter, allows all three channels to pass through evenly. So we can apply this theory to the colour temperature problem of different light sources. Our halogen inside shots are too red, so we'll want a filter that blocks some of that red channel from coming through. A "correction filter", buzzword. After the filter the colour of the shot is better, but whenever you put a filter in front of a light source you take a certain portion of it's strength. So perhaps you'll have the right colour, but you'll need more or a greater light sources. Light sources An average household bulb is roughly 60-100 watts. Lightbulbs have a low colour temp, end of story. After a whole range of degrees you get up to your average halogen theatre spot which will be roughly between 1000watts or 2kw (kilowatts) . After that it goes up in bigger steps: 5kw and 10kw are used in film shoots. However, they are still lightbulbs, and therefore still have a relatively low colour temperature: You may have much more light, but you'll still have a lot of red. Gas based lights, such as TL, have a much higher colour temperature and use much less power. For example, disco lights, those ones that move around a lot at your local club, all use gas based bulbs. Gas burns in a contained area and produces serious amounts of light. These disco spots will range from 250watts to maybe 1.5kw tops. There are of course exceptions, but on the whole that's what you'll find. After the light source, you can achieve different effects by sending it through a lens, Widening the bundle, focusing it to be sharp or soft. Making shapes is also possible with various lenses and shutters. When you see a sharp focused light you know that it has at least two lenses. A soft lighting fixture will generally only have one lens. The more lenses you pass the light through the less light you have left over in the end. Light source correction filters The company LEE is one of the leading sources of light filters. Their correction filters range from L201 (tungsten to daylight) through to L205 (daylight to tungsten), tungsten being the type of filament that glows in a lightbulb or halogen light to produce light. With these filters you can easily correct your light source to the desired colour temperature Practical uses Enough initial blah, now to the practical uses and how to generate a nice shot. When I say front light, side light, or backlight I'm talking in reference to the camera. If, in a completely dark room you shine a flashlight at something, you only have one frontal light source so the object itself will appear two-dimensional or quite flat because you are facing the same direction as the light. This is completely true for humans too, a shot of someone with only frontal light will appear very flat. A shot with only backlight and you'll only see a silhouette of the object, again not much depth. A good basis to work from is a three point lighting. In the case of a person, one from behind, one from left front and one from right front. These frontal angles are based on the surfaces of the human face. If all three light sources are equally strong then the object will be fully lit leaving very few shadows. This is good for an instructional video where you want everything to be as visible as possible. To create little more atmosphere it's good to play around with the levels of the light sources. A standard for concerts would be to have a strong backlight to create a nice outline and then lesser values for the front lights to fill in shadows, and also to have different values again for the front lights to create a more natural look. One side has more of an accent than the other giving a more 3-d view. Three point lighting is functional but about as safe as it gets. The image you get can be a little static sometimes which is fine if your object is not moving too much, but if your film is based on movement it is nice to use side light. Movement will seem more dramatic with side light. Its hard to explain, but it has to do with the front surface of the object not really having so much light, only the sides of the objects having side light will give them a sort of outline which is easy for the eye to trace, making the movement seem bigger. Just experiment with it. Well that’s about it for the moment. This is as basic as it gets but hopefully it'll give you some understanding of whatever you hadn’t figured out on your own. Light is absolutely essential to film making, simply the most important factor, and it can take a whole lot of thinking about. |