How Photography Works and Has Evolved

Photography

What is photography and how has it evolved? Photography has been around since 1000 A.D. The first camera was called a Pinhole Camera, invented by Alhazen in the 1500’s. “The exposure time on taking the photo was fifteen to twenty seconds in a sunny scene.” (Hawshaw 1) Photography was and is used to take family portraits and even for studies. Today with the power of digital photography any one can take one picture or one hundred. It’s only a click of a button away with today's cameras. Cameras have changed the evolution of photography.

Photography is the process of making pictures by the action of light. Light reflected from a subject forms an image of that subject on a light-sensitive device, called a camera, onto a paper-like material, called a picture. The image formed by light is then digitally or chemically processed into a photograph. The word photograph is combined from two different greek words. Photo comes from the greek word light, and graph comes from the greek word to write or draw. Altogether photography means to write or draw with light.

Photography can be used to help our lives in many different ways. Photography can help us learn about other parts of the word and even history. Photos also help us keep memories with us, to see them whenever we would like. Special cameras can help us capture images in places humans can’t reach or go. Photos made by visible light, X-Rays, infrared rays, or other forms of radiant energy help physicians detect many types of sicknesses. Cameras can also “see” events that the eye cannot. Some cameras can record action that occurs rapidly, but we see it as a blur. Through this, scientists can examine fast moving objects. There are many different fields or research photog...

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...autofocus system electronically analyzes the image formed by the lens. The system detects the contrast—that is, the difference between the light and dark areas—and the hardness of the edges in the image. An image generally is in focus when it reaches maximum contrast and has hard edges, and so the system adjusts the lens until this point is reached.

SLR cameras have a focusing screen where the photographer can see and manually focus the image. When light enters the camera and forms the image, a mirror reflects the image onto the focusing screen, which is viewed through the viewfinder window. Some focusing screens use a microprism, a split-image prism, or both. These focusing aids cause part of the image area to appear broken up or not aligned if the image is not focused. Rangefinder cameras have a focusing system that works in a similar way to the split-image prism.