This term refers to the sharpness, or detail, of a picture. The higher the number of pixels, the higher the resolutions. You can determined the resolution you need by determining what you really want to do with these pictures. Picture size is measured by how many pixels make up an image and is measured by horizontal by vertical resolution, as in 1280 x 960. The manufacturers break this down to about 5 main different categories of resolutions, expressed in mega pixels. Here is the breakdown:
1 megapixel cameras - these are nearly obsolete. They are good for posting images to the Internet, looking at images on a monitor, and emailing photos. Cell phones and camcorders tend to have around 1 megapixel capability.
2 megapixel cameras - the maximum resolution here is 1600 x 1200, which is better than the resolution of most computer monitors. Also good for posting pictures to the Internet, viewing images on a monitor, and emailing. It can also print images up to 8x10 inches, and will allow you to do basic graphics work.
3-5 megapixel cameras - a 3 megapixel camera will print up to 11x14 inch images. If you are not a professional, this is probably as detailed as you need to get. It does everything a 2 does, plus allows you to do professional graphics work. The cost of a 3 megapixel camera is much more reasonable than that of a 4 or 5, but still allows you to have great flexibility in use. 4 and 5 mexapixel cameras will have even larger images and print sizes.
Digital cameras store pictures as data files rather than on film. The size of your memory determines the number of pictures you can take before downloading the images to a computer, at which time you can go back and fill the memory up with new pictures. Most cameras come with only 8 megabytes (MB) of memory, which for a 2 or 3 mega pixel camera could be only 10 to 40 photos. More memory is available by buying removable memory, such as a memory card. The type of memory you buy will be determined by the type of camera that you buy. 128MB of memory is a good starting place, allowing you to take a good number of photos before having to download to your PC.
A flash, of course, is the extra light needed to shoot inside or in low-light conditions. Most digital cameras have built-in flash with a range of 10 to 16 feet. Other flash options include:
Red Eye Reduction - Two flashes are emitted, the first to contract the iris so that the eye doesn't reflect as much light with the second, which keeps friends and family member from looking fiendish in the photo.
External Flash - More powerful than automatic, this allows you to attach the flash to the camera and place it strategically. The types include "flash sync" and "Hot Shoe." Cameras that include external options will generally have automatic flash as well.
Burst Mode - known also as Rapid Fire and Continuous Shooting mode. In general, there is a 1-2 second time lag between pressing the shutter button and a picture being taken with a digital camera. Then there is a 2-30 second recovery time before the camera is able to take another photo. With the Burst Mode feature you can take several pictures in a row. This useful for taking shots in motion, such as children playing or sports events.
Optical Zoom - there are 2 types of zoom lenses, digital and optical. Digital zoom simply enlarges the picture without adding any clarity of detail. The same thing can be done with editing and cropping software. Optical zoom will do what you really want; add detail and sharpness. The larger the lens (2x, 3x, which is standard, 4x, etc.) the more picture taking flexibility you have.
More Features of Digital Cameras
Compression - this process shrinks the file size of a photo. Uncompressed photos are clearer, the files are enormous and require huge amounts of memory. JPEG format compresses the files, allowing you to store more, save, download, and email photos at a faster rate. For general use, JPEG is fine.
Power Source - digital cameras are voracious eaters of batteries. They use either a rechargeable battery pack or traditional batteries, usually 2 - 4 double A. Some have an AC adapter as well. For rechargeable batteries, which you want unless you really like to buy a lot of batteries, and often, NIMH batteries can be charged up to 1000 times, while Lithium Ion batteries can also be charged up to 1000 times and last twice as long as NIMHs.
Lens - lens length will determine how much of a scene will fit into a picture. Some cameras have fixed focus lenses, which are preset to focus at a certain range. These pictures typically focus between a wide angle lens and normal range. Many cameras have auto focus, which pick an item in the center of the viewfinder around which to focus. To get an idea of a camera's range, it will be listed as the 35mm equivalent.
Focus and Exposure - most cameras have auto focus, but higher end cameras will include a manual focus capability. Panorama picture taking is available, as well as various types of light sensitivity. For instance, a camera rated at ISO 100 has approximately the same light setting as a normal camera using ISO 100 film. The higher the ISO setting, determined by the aperture, the less light a camera needs to take a good image.
LCD Screen - this screen will let you see what the photo will look like and, typically, let you see what you've already taken and erase what you don't need. The screens use a lot of power, but are very desirable for editing purposes. Some cameras will let you display multiple pictures on the LCD screen at one, usually 9 or 12 at a time.
Self-Timer - this is an option that lets the photographer be included in the photo. Self-timers have a pre-set delay, usually giving you about 10 seconds to run into the shot. There are also cameras with a remote control option to work the shutter.
Manual Features - available on high end cameras, these give more serious photographers more creative control. They include things such as focus, aperture speed, and shutter speed. Read the options carefully, as each camera can have a different meaning for manual.