Halogen-Metal-Iodide

On feature films, lighting is exceptionally important. It is usually the Director of Photography’s responsibility to make sure that the lighting design is perfect, not only the camera positions and how the scene will be shot. The lighting affects the dramatic intensity of the scene, and has a very powerful effect. In this essay I will be discussing the different types of lighting units, focusing mainly on interior lighting units. I will mention different types of bulbs, as well as explain briefly what Colour Temperature is. I will also show what the different kinds of lights are used for.

Lighting Units Lighting units are what we refer to as bulbs, lambs or globes. They are identified by type and power consumption, for example a 5K spot is a 5000-watt (5-kilowatt) spotlight. The lights are usually balanced for Tungsten (3200i?? K). The brightness of a bulb is indicated by its wattage. The term “falloff” refers to the rate of change from light to shadow. The rule for typical open bulbs is that the falloff in intensity is inversely proportional to the square of the distance, thus, moving an object twice as far from a lamp results in it being lit by 1/4 the amount of light.

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This means that falloff will be exceptionally sharp the nearer you are to the light source, therefore soft light sources will have a sharper falloff than focused, hard light sources. Bulbs There are many different types of bulbs, and they differ in the type and colour of light that they emit. Household bulbs can be used with video, as long as the DP is able to maintain a good white balance. Because the colour temperature is only about 2900i?? K, they produce a yellow-orange light instead of white on tungsten-balanced colour film. They are mainly used in practical fixtures, such as a side or table lamp in a scene.

Photo bulbs can be either photofloods or reflector floods. A photoflood is a lamp used by photographers, which gives a bright white light. Because they have a thin filament, they give a good flash effect (e. g. lightning). They have a relatively short life, however, so they should not be left on for any length of time. Tungsten-halogen bulbs employ a tungsten filament surround by halogen gas encased in a quartz crystal bulb. During the lamp’s life, tungsten evaporates from the filament, and would normally deposit itself on the glass wall of a tungsten lamp.

This would make it blacken; causing the output of the lamp to reduce until it finally blew. In a tungsten halogen lamp, the tungsten combines with the halogen gas elements present in the lamp envelope and is re-deposited back onto the filament. This process needs a very high temperature to operate, so tungsten halogen lamps are able to be a lot smaller, and run a lot hotter, than their tungsten equivalents. An HMI (Halogen-Metal-Iodide) bulb is a mercury-halide discharge lamp with a colour temperature of 5600i?? K or 6000i?? K (daylight balance illumination).

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