| Resolution | | | | but fairly limited. |
| The amount of detail that a camera can capture | | | | 2) Optical-zoom lenses with automatic focus - |
| is called the resolution, and it is measured in pixels. | | | | Similar to the lens on a video camcorder, these |
| The more pixels a camera has, the more detail it | | | | have "wide" and "telephoto" options and automatic |
| can capture and the larger pictures can be | | | | focus. The camera may or may not support |
| without becoming blurry or "grainy." High-end | | | | manual focus. These actually change the focal |
| consumer cameras can capture over 12 million | | | | length of the lens rather than just magnifying the |
| pixels. Some professional cameras support over | | | | information that hits the sensor. |
| 16 million pixels (megapixels), or 20 million pixels | | | | 3) Digital-zoom lenses - With digital zoom, the |
| for large-format cameras. For comparison, it has | | | | camera takes pixels from the center of the |
| been estimated that the quality of 35mm film is | | | | image sensor and interpolates (alters) them to |
| about 20 million pixels. | | | | make a full-sized image. Depending on the |
| Exposure and Focus | | | | resolution of the image and the sensor, this |
| Just as with film, a digital camera has to control | | | | approach may create a grainy or fuzzy image. |
| the amount of light that reaches the sensor. The | | | | You can manually do the same thing with image |
| two components it uses to do this, the aperture | | | | processing software -- simply snap a picture, cut |
| and shutter speed, are also present on | | | | out the center and magnify it. |
| conventional cameras. | | | | 4) Replaceable lens systems - These are similar |
| Aperture: The size of the opening in the camera. | | | | to the replaceable lenses on a 35mm camera. |
| The aperture is automatic in most digital cameras, | | | | Some digital cameras can use 35mm camera |
| but some allow manual adjustment to give | | | | lenses. |
| professionals and hobbyists more control over the | | | | Storage of Images |
| final image. | | | | Most digital cameras have an LCD screen so you |
| Shutter speed: The amount of time that light can | | | | can view your picture right away. This is one of |
| pass through the aperture. Unlike film, the light | | | | the great advantages of a digital camera -- you |
| sensor in a digital camera can be reset | | | | get immediate feedback on what you capture. Of |
| electronically, so digital cameras have a digital | | | | course, viewing the image on your camera would |
| shutter rather than a mechanical shutter. | | | | lose its charm if that's all you could do. You want |
| These two aspects work together to capture the | | | | to be able to load the picture into your computer |
| amount of light needed to make a good image. In | | | | or send it directly to a printer. There are several |
| photographic terms, they set the exposure of the | | | | ways to do this. |
| sensor. | | | | Although most of today's cameras are capable of |
| In addition to controlling the amount of light, the | | | | connecting through serial, parallel, SCSI, USB, or |
| camera has to adjust the lenses to control how | | | | FireWire connections, they usually also use some |
| the light is focused on the sensor. In general, the | | | | sort of removable storage device. Digital cameras |
| lenses on digital cameras are very similar to | | | | use a number of storage systems. These are like |
| conventional camera lenses -- some digital | | | | reusable, digital film, and they use a caddy or card |
| cameras can even use conventional lenses. Most | | | | reader to transfer the data to a computer. Many |
| use automatic focusing techniques. | | | | involve fixed or removable flash memory. Digital |
| The focal length, however, is one important | | | | camera manufacturers often develop their own |
| difference between the lens of a digital camera | | | | proprietary flash memory devices, including |
| and the lens of a 35mm camera. The focal length | | | | SmartMedia cards, CompactFlash cards and |
| is the distance between the lens and the surface | | | | Memory Sticks. Other removable storage device |
| of the sensor. Sensors from different | | | | include floppy disks, hard disks (external, or |
| manufacturers vary widely in size, but in general | | | | microdrives), and writeable CD's and DVD's. |
| they're smaller than a piece of 35mm film. In | | | | Regardless of what type of storage they use, all |
| order to project the image onto a smaller sensor, | | | | digital cameras need lots of room for pictures. |
| the focal length is shortened by the same | | | | They usually store images in one of two formats |
| proportion. | | | | -- TIFF, which is uncompressed, and JPEG, which |
| Focal length also determines the magnification, or | | | | is compressed. Most cameras use the JPEG file |
| zoom, when you look through the camera. In | | | | format for storing pictures, and they sometimes |
| 35mm cameras, a 50mm lens gives a natural | | | | offer quality settings (such as medium or high). |
| view of the subject. Increasing the focal length | | | | To make the most of their storage space, almost |
| increases the magnification, and objects appear to | | | | all digital cameras use some sort of additional data |
| get closer. The reverse happens when decreasing | | | | compression to make the files smaller. One |
| the focal length. A zoom lens is any lens that has | | | | compression routine takes advantage of patterns |
| an adjustable focal length, and digital cameras can | | | | that repeat. The image can be reconstructed |
| have optical or digital zoom -- some have both. | | | | exactly as it was recorded, reducing the file size |
| Some cameras also have macro focusing | | | | no more than 50%, often much less. Another |
| capability, meaning that the camera can take | | | | compression routine called irrelevancy eliminates |
| pictures from very close to the subject. | | | | some of the more meaningless data, taking |
| Digital cameras have one of four types of lenses: | | | | advantage of the fact that digital cameras record |
| 1) Fixed-focus, fixed-zoom lenses - These are the | | | | more information than the human eye can easily |
| kinds of lenses on disposable and inexpensive film | | | | detect. |
| cameras -- inexpensive and great for snapshots, | | | | |