camera


 * single-lens-reflex** (SLR) camera. This is a camera where the photographer sees exactly the same image that is exposed to the film and can adjust everything by turning dials and clicking buttons. Since it doesn't need any electricity to take a picture, a manual SLR camera provides an excellent illustration of the fundamental processes of photography.

The optical component of the camera is the **lens**. At its simplest, a [|lens] is just a curved piece of glass or plastic. Its job is to take the beams of light bouncing off of an object and redirect them so they come together to form a **real image** -- an image that looks just like the scene in front of the lens.

In a standard **converging**, or **convex** lens, one or both sides of the glass curves out. This means rays of light passing through will bend toward the center of the lens on entry. In a **double convex lens**, such as a magnifying glass, the light will bend when it exits as well as when it enters. =Cameras: Focus= We've seen that a **real image** is formed by light moving through a convex lens. The nature of this real image varies depending on how the [|light] travels through the lens. This light path depends on two major factors:
 * The angle of the light beam's entry into the lens
 * The structure of the lens

In a **zoom lens**, you can move different lens elements back and forth. By changing the distance between particular lenses, you can adjust the magnification power -- the focal length -- of the lens as a whole. Professional cameras let you attach different lenses so you can see the scene at various magnifications. The magnification power of a lens is described by its **focal length**. In cameras, the focal length is defined as the distance between the lens and the real image of an object in the far distance (the moon for example). A higher focal length number indicates a greater image magnification.

**I**n smaller productions, the producer may also take charge of the more mundane activities. And in small productions, the //director// may handle the producer's responsibilities. In this case, the combined job title becomes (want to guess?), ▲producer-director. [|Conventional cameras] depend entirely on chemical and mechanical processes -- you don't even need electricity to operate them. On the other h­and, all digital cameras have a built-in computer, and all of them record images electronically. When you get down to it, [|CDs], [|DVDs], [|HDTV], [|MP3s] and [|DVRs] are all built around the same basic process: converting conventional analog information (represented by a fluctuating wave) into digital information (represented by ones and zeros, or [|bits]). This fundamental shift in technology totally changed how we handle visual and audio information -- it completely redefined what is possible. A **beam splitter** directs light to the different sensors. Think of the light entering the camera as water flowing through a pipe. Using a beam splitter would be like dividing an identical amount of water into three different pipes. Each sensor gets an identical look at the image; but because of the filters, each sensor only responds to one of the primary colors. Another method is to **rotate** a series of red, blue and green filters in front of a single sensor. The sensor records three separate images in rapid succession. The image sensor employed by most digital cameras is a **charge coupled device** (CCD). Some cameras use **complementary metal oxide semiconductor** (CMOS) technology instead. Both CCD and CMOS image sensors convert light into electrons. If you've read [|How Solar Cells Work], you already understand one of the pieces of technology used to perform the conversion. A simplified way to think about these sensors is to think of a 2-D array of thousands or millions of tiny solar cells. more economical and practical way to record the primary colors is to permanently place a filter called a **color filter array** over each individual photosite.

The most common pattern of filters is the **Bayer filter pattern**. This pattern alternates a row of red and green filters with a row of blue and green filters.