29 Jun

Photography Science Lesson 1 Light

Visible light is a small portion of the electromagnetic radiation spectrum. What's electromagnetic radiation? Sound dangerous. Well it depends on where along the spectrum you're talking about. But to the point. Electromagnetic radiation is the synchronized oscillation of electric and magnetic fields. Or two waves of equal height (wavelength) and length per wave (frequency ), one electric field and one magnetic field traveling in phase along the same axis at the speed of light. Technically light travels at the speed of electromagnetic radiation. But they way our science evolved determined how our language was built, so we use 'light speed' and 'speed of light.' Because we discovered light before Scottish scientist James Clerk Maxwell discovered electromagnetic waves, and published his findings in 1865. Sadly his peers didn't give him much heed on those findings at the time. Moving on.

Electromagnetic waves are created whenever subatomic particles (things smaller than atoms like electrons) are accelerated.

Atoms are made of a nucleus, with electrons orbiting them. To put it crudely, electrons orbit in layers. The last layer is called the valence shell. Just like moving away from a planet or star the further away from the object the less gravity. The electrons in the valence shell generally have the most energy. A photon is produced when an electron that has moved from it's further than natural orbit returns to its regular orbit. A photon is a burst of electromagnetic radiation which falls in the visible (white) light spectrum. They are a form of energy and have no mass.

Photons can interact with matter in several ways. Photons can pass through certain matter with no effect. This is what is sought after with high quality lenses. Photons can be refracted, that is its direction can be changed and its wavelength is either increased and/or decreased while it's frequency remains the same. Photons can be adsorbed by the matter. Or photons can be reflected.

So within your camera, ideally you're having everything but refraction happening. You want it to pass through your lens with no effect. If you're using an SLR/DSLR the light is reflecting off the reflex mirror and pentaprism while you setup your shot, and being absorbed by the film or censor, once the reflex mirror is raised and the shutter opens. You will encounter refraction when there are oils, scratches, or pits on your lens, and heaven forbid your censor.

So back to the science. When photons pass through things, nothing much visual happens. When photons are refracted the light can bend (images distorted) and wavelength changed, and more. When light is reflected it makes for good shots with water bodies and such and more. What about when light is absorbed? When light is absorbed it is converted to heat.

What are these "and more" statements of the last paragraph about? On to Photography Science Lesson 2 Color.

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