All digital pictures are composed of tiny dots, called pixels, which are arranged in a grid. A megapixel corresponds to roughly one million pixels. Megapixels are used to describe the precision of a digital camera. The more megapixels, the more details a camera can capture.

6 Megapixels	3 Megapixels	1 Megapixel

Optical zoom is the ability of a camera to photograph a smaller area from a given point of view. The effect is very similar to getting closer except that perspective changes, meaning that the relative distance between objects does not always stay the same. Optical zoom is measured by how much closer the camera can get compared to its widest setting. For example, a 2X optical zoom can make a subject appear twice as close.

Original	Optical zoom 4X

Digital zoom refers to a digital camera's attempt to emulate optical zoom. Digital zoom gives the impression of getting closer to a subject without actually capturing any more detail. Digital zoom is the equivalent of cutting the center of a picture and blowing-up just that portion. Digital zoom must be ignored when purchasing a digital camera because it can easily be done better by computer after a picture is taken.

 

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LCD stands for liquid crystal display. It refers to the small screen on the back of a digital camera which is used for viewing the pictures you took and, in most cases, to preview the picture you are about to take. When an LCD previews the image correctly, it is called exposure-priority as opposed to display-priority, which shows a bright and clear image regardless of exposure.

 

LCDs are described by their size and by their resolution. High-end cameras, called DSLRs, are normally used through an optical-viewfinder (OVF) but recent models can sometimes preview images as well, although either with slow autofocus or incomplete frame-coverage.

This is the part of the camera that can be used to look at a subject. While an LCD can be used as a viewfinder in most cameras, the majority of digital cameras also have either an optical viewfinder or an electronic viewfinder, called EVF. When the photographer sees through the camera it is called an optical viewfinder. Optical viewfinders show less than what will be pictured. An EVF is a miniature LCD showing the same thing as the camera's main LCD. An EVF shows exactly what will be pictured but not as precisely as the human eye.

This is a type of camera mostly used by professional photographers which is made so that the viewfinder actually looks through the lens of the camera. All current Digital SLR cameras allow their lenses to be changed. Digital SLR cameras are usually sold without a lens.

A flash on a digital camera, just like on a film camera, is a small lamp that can add light to close by objects when a picture is taken. A pop-up flash is normally hidden and pops-up when required. A flash is described by the maximum distance of objects it can sufficiently illuminate when the lens is wide-open and when it is completely zoomed-in.

 

No flash	Flash

A very common feature of modern digital cameras is the ability to produce short video clips. These clips are made by rapidly taking a sequence of low-resolution images.

 

Movie mode is described by its resolution, frame-rate, duration and its ability to record sound or not. No DSLR has a movie mode.

 

	HD video has a resolution of at least 1280x720 and as high as 1920x1080.
	High resolution video has more than 320x240 pixels. Most commonly it has VGA resolution or 640x480.
	Low resolution video is 320x240 (Quarter VGA) or less.