How do digital cameras work?
In contrast to a conventional film camera, in a digital camera the light is focused onto an image sensor called a CCD (charge coupled device). The CCD is a collection of light-sensitive photosites that produce an electric charge when struck by light. These charges are converted into numbers that are stored in the memory (usually on a memory chip). From there, the whole image can be displayed, sent to a computer, or even printed directly on a printer.
What resolution do I need for high quality pictures?
For 4 inch by 6 inch pictures, you need at least 0.9 megapixels. For 5x7 prints, you need at least 1.3 megapixels. For 8x10 prints, you need at least 3.0 megapixels. For 8.5x11 prints, you need at least 3.5 megapixels. For putting up pictures on web sites, a 2.0 megapixel camera should be enough.
What is lens aperture?
Lens aperture or the f-number is the ratio of the focal length of the lens to the diameter of the light rays passing through the aperture in the iris diaphragm. Smaller numbers represent bigger openings and allow more light to pass through. F-number settings are adjustable; lenses are marked with their maximum aperture (lowest f-number).
How does aperture affect depth-of-field?
Larger aperture (smaller f-number) produces shallower depth of field. Depth of filed affects how far away from the focus point the objects can be before they become increasingly blurred in the resulting picture.
How many pictures will fit in the memory?
The exact number depends on the size of the memory card (or other type of storage used), the camera's resolution, the compression quality setting, the exact type of camera, and even the type of pictures taken. For example, a 3 megapixel camera might make 0.8 MB pictures at the highest JPEG quality setting, therefore fitting about 160 pictures on a 128 MB card.
What are SLR digital cameras?
In an SLR (Single Lens Reflex) camera, the user is seeing exactly what the camera is seeing through a series of prisms and mirrors. This becomes important for more advanced photographers. In SLR cameras, it is also possible to interchange lenses and keep the lenses from other cameras. Many digital SLR cameras also offer higher resolution since they are aimed at the pros. The disadvantages of SLR digital cameras are the significantly higher costs, bigger size and weight, and a small delay before the photo is taken because the mirror has to move out of the way before a shot.
