Nikon D90 Digital Camera with 18-105mm lens

There are several different types of digital cameras. Compact & Ultra-compact are light, pocket-sized cameras that are easy to carry, usually with a built-in lens. Standard point-and-shoot cameras are of medium size, usually come with a built-in lens, & have basic features that are useful for the casual photographer. SLR/Professional cameras are usually larger, but offer more advanced features & detachable lenses for the photography enthusiast or professional.

The sensor in a digital camera is composed of pixels, which are tiny light-sensitive squares. The sensors in most cameras today are made up of millions of pixels, each one registering the brightness of the light striking it as the photo is taken. A megapixel is the term used for a million pixels ” & the more megapixels an imaging sensor has, the higher the camera's potential resolution. On the other hand, the megapixels determine the size of the print, so higher megapixels means larger print sizes, for examples, 6 megapixels are good for 8 x 10 in. prints, 8 megapixels are good for 16 x 20 in. prints.

The optical zoom ratio of a digital camera measures how much the lens can actually zoom in to make subjects appear closer. Be careful to not confuse optical zoom with digital zoom. Optical zoom actually enlarges a picture while keeping the resolution & sharpness of the picture high.

Unlike optical zoom, digital zoom magnifies the pixels but not the actual image. The resulting image appears bigger, but is not as sharp as with an optical zoom.

Higher-end cameras may allow you to separate the camera body from the lens, allowing you to interchange lenses for different types of photography.

The optical zoom ratio of a digital camera measures how much the lens can actually zoom in to make subjects appear closer. Be careful to not confuse optical zoom with digital zoom. Optical zoom actually enlarges a picture while keeping the resolution & sharpness of the picture high.

The distance from the center of the lens to the image of an object at infinity. At same size, the distance from copy to image is four times the focal length of the lens. This also applies to lithographic process lens as well. A 35mm SLR camera has interchangeable lenses that can range in focal length from around 7 to 17mm which are usually fisheye, 17 to 35 are considered wide angle. 50mm is called the standard lens as it has the same equivalent focal length as the human eye. Anything longer is a telephoto lens. Usually expressed in millimeters, smaller focal lengths result in wider fields-of-view.

A CCD sensor will provide a sharper more precise image, but is generally more power consuming. CMOS sensors are generally more energy efficient & are creating better & better images as technology develops.

Resolution is measured in megapixels. The higher the megapixels, the sharper & more detailed the pictures your digital camera can take, & the bigger you can enlarge them without losing the sharpness of the image. 3.1 megapixels & higher is usually considered sufficient for print-quality photos. Photos with a resolution of less than 3.1 megapixels are best viewed only on computers.

The sensor in a digital camera is composed of pixels, which are tiny light-sensitive squares. The sensors in most cameras today are made up of millions of pixels, each one registering the brightness of the light striking it as the photo is taken. A megapixel is the term used for a million pixels ” & the more megapixels an imaging sensor has, the higher the camera's potential resolution. On the other hand, the megapixels determine the size of the print, so higher megapixels means larger print sizes, for examples, 6 megapixels are good for 8 x 10 in. prints, 8 megapixels are good for 16 x 20 in. prints.

Many digital cameras let you record short clips of highly compressed, low-resolution video, either as an MPEG movie or a Motion JPEG movie. This number shows the actual optimal size for a movie captured on your camera.

The aperture range measures how much light is let into the camera when taking a photo. Low f-stop settings are best for low light photography while higher f-stops provide a greater depth of field.

The shutter speed of a camera depends on two variables: the size of the lens & the actual timing of the shutter, opening & closing. These two factors work as a team to control the amount of light that enters the camera. This is measured in fractions on a shutter speed dial which illustrate how long the shutter opens & closes in a set period of time. The term speed refers to how long the lens remains open. For example, a setting of 1/60 on a shutter speed dial means that the shutter opens & closes within one sixtieth of a second. Various shutter speeds can be used to manipulate the final result of the picture. Usually, a faster shutter speed is used to freeze the scene, for motion shots, while a slower speed is used to create more of an unfocused, abstract result.

The white balance of a digital camera controls the color outcome of pictures. All light gives off a color temperature which the camera analyzes & internally adjusts, so that the colors of the picture are captured in their true form. Without the proper white balance, the color in a photo may contain an overabundance of blue, green or orange hues.

There are many types of memory / media for digital cameras, but most models are compatible with only one. The most common are CompactFlash & SmartMedia. Many other cameras use Memory Stick & some write the pictures directly onto mini-CDs or floppy disks. It is helpful to choose some sort of memory device that is easy to find in stores, in case you need to purchase extra.

Many cameras include different settings to control photo resolution. The resolution of the pictures you take affects their quality as well as the amount of memory they utilize. Higher resolution results in higher quality, but takes up more memory.

ISO stands for International Standards Organization. It denotes the rating of a film's sensitivity to light (based on an arithmetical progression). Though digital cameras don't use film, they have adopted the same rating system for describing the sensitivity of the camera's imaging sensor. Digital cameras often include a control for adjusting the ISO speed; some will adjust it automatically depending on the lighting conditions, adjusting it upwards as the available light dims. For exampe, ISO 200 film is twice as fast as ISO 100 film but only half as fast as ISO 400. The scale is identical to ASA (American Standards Association). Generally, with higher ISO speeds there is more noise.

If the camera has a built-in flash, it might have several different flash functions, such as on/off or anti-redeye flash.

A viewfinder is the small square on the back of a camera that you look through to compose the scene. Some cameras have small screens on the back that act as viewfinders. Other cameras have small glass areas through which you can look out of the front of the camera.

LCD stands for "Liquid Crystal Display." This is the small screen on the back of a camera that digitally displays the same image you would see through the viewfinder. On many cameras you can also review the pictures stored in the camera's memory on the LCD Panel.

The method by which your camera will communicate with your computer or other video device. Different methods enable you to download photos at varying speeds. Make sure the interface you want is also compatible with the computer you want to use it with.