What Is An SLR
SLR stands for Single Lens Reflex. It is called a single lens reflex camera, in part, to differentiate it from a twin reflex camera, and because you see your subject indirectly through the lens by way of a mirror and pentaprism. A twin lens relex uses two identical lenses, one above the other. One lens is used for focusing and the other for taking the picture. And a view camera looks directly through the lens to frame a subject. Other cameras which do not view the subject through a lens, but a simple viewfinder, are more difficult to frame a subject as wanted. With an SLR, you see exactly what your are getting, for the most part. Many viewfinders on SLRs don't show a 100% view, but for a small area around the edges you'll see exactly how you are framing your shot. It's basically what you see is what you get. One doesn't get parallax error as in simple viewfinder style cameras.
Of all cameras, an SLR is the most versatile. A very wide variety of lenses can be interchanged. Numerous accessories are available to aid or enhance your photography, such as battery and data backs, various filters and closeup lenses, flash units, motor drives, and remote shutter releases, just to name a few. SLR cameras which are 35mm or digital format are the cameras of choice for most professional photographers, especially those in photojournalism, travel, and nature photography.
SLR cameras can vary in the functions and controls they have available, depending on model, but two of it's most useful functions are through the lens metering (TTL), and for those that have it, a depth of field preview button or switch, which allows one to see what will be exactly in focus and what will be blurred within their composition.
If you want to be a serious and/or creative photographer, an SLR is the best choice because of its versatility and creative abilities. An SLR allows you to change lenses, all the way from very wide angle fisheye's to long telephoto and zoom lenses. They can be used with a variety of light sources. They have a wide variety of shutter speeds. And some allow double exposures and timed shutter release. All of which add to the creativity of the photographer.