06_light_optics_film

06_light_optics_film - 10/10/2007 10/10/2007 Welcome to...

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Unformatted text preview: 10/10/2007 10/10/2007 Welcome to Digital Media Technical Theory BDC111: Visual and Digital Media What is light? Is it a wave... Or a particle? Actually, Actually we sometimes think of it as both... Making Light Incandescence heating something up (that's why they call it a `candle') - this includes light bulbs Fluorescent lights - use electricity to directly energize atoms Lasers - use energy to "pump" a lasing medium, all of the energized atoms dump their energy at the exact same wavelength and phase Glow-in-the-dark toys - electrons are energized by light, but only for a while Backlit watches - voltage energizes phosphor atoms Chemical light sticks and fireflies - use a chemical reaction to energize atoms ALL of these things energize atoms What is light? Particle P ti l Travels in straight lines Bounces like a ball Gets absorbed like a ball 1 2 10/10/2007 10/10/2007 What is light? Wave Thomas Young What is light? http://static.howstuffworks.com/flash/light-waves.swf What is light? Wave Thomas Young What is light? It's a wave, but not like water An electromagnetic radiation Which means it has both electrical and magnetic properties And can be, in fact, attracted and repelled by both magnetism and electrostatic charges y This is very similar to radio waves, but with an important difference Your eyes are the "radio receivers" of light ...and no batteries are required... 3 4 10/10/2007 10/10/2007 What is light? What is light? So, it's clear that light can be focused And that ability means that focused light energy can be used to change matter from one form to another h And not just for burning... Like all energy, it can b converted be d into other forms of energy Like heat... 5 6 10/10/2007 10/10/2007 Film How many photographers in the crowd? How many of the photographers have done their own film and p print developing? p g Film The silver halide is converted to pure silver when immersed in a developing bath. More development time means more silver halide is converted to silver. Film When exposed to light, changes happen in a chemical coating (silver halide) on the film surface Silver halide is sensitive to light g Film The leftover silver halide would cause the picture to darken over time (it's still (it s sensitive to light, remember), so the negative is immersed in a "fixer" bath of thiosulfate compound to prevent this from happening 7 8 10/10/2007 10/10/2007 Film As you can see from this picture, wherever the light hit the film, it is now dark we've just created a photographic negati e negative This negative can then be put into an enlarger (which is essentially like a slide projector, making the image bigger) and this negative image can be shone onto photographic paper that's just like film, except it has a paper backing instead of a clear backing When Light Hits An Object The waves can be reflected or scattered off the object. The waves can be absorbed by the object. The waves can pass through the object with no effect effect. So far...this is really similar to sound waves... We'll talk about colour film later in the lecture, but there's a few things we have to understand about light and the g nature of colour, first... When Light Hits An Object The waves can be reflected or scattered off the object. The waves can be absorbed by the object. The waves can pass through the object with no effect effect. The waves can be refracted through the object. 9 10 10/10/2007 10/10/2007 It's made up of a whole bunch of different wavelengths all f diff t l th ll mushed together...what we see is the addition of those different colours, which appears to us as white light... 11 12 10/10/2007 10/10/2007 The frequency of visible light is referred to as colour, and ranges from 430 trillion Hz, seen as red, to 750 trillion Hz, seen as violet. The wavelength of light is from around 400 to 700 nanometers (400 to 700 billionths of a meter) 13 14 ...
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This note was uploaded on 10/20/2008 for the course BDC 111 taught by Professor Danalee during the Fall '08 term at Ryerson.

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