What Are Digital SLR Cameras?

SLR stand for "Single Lens Reflex," which means when the photographer looks through the view finder, the photographer is seeing exactly what the lens sees. By being able to see through the lens , the photographer knows exactly how the image will look when taken. Paired with manual settings, the photographer can have complete control of the image, which is why the SLR is the preferred camera professional photographers.

Point and Shoot vs SLR

With point and shoot cameras, when the photographer looks through the view finder, they are not looking through the lens. The view finder is calibrated to be a representation of what the lens sees. Point and shoot cameras also do not have as many (if any) manual settings as the SLR, so the photographer cannot control every aspect of the picture.

Conrtoling Aspects of the SLR

With the manual settings on the SLR, the photographer can control the ISO (or film speed), shutter speed and aperture. The ISO (or film speed) controls how sharp the image is and how sensitive the optical disk (or, in film camera's, the film) is to light. The aperture is the hole in the lens that controls how much light can be let in. The shutter speed controls how long the light is let in for. All these things contribute to the exposure of the image. It is taking control of these aspects that can give an picture a motion blur, ambient lighting and different depths of field.

Lenses

SLRs have interchangeable lenses. It's these lenses that make it possible to have complete control of the aperture, focusing and distance. Every lens has a different use. Telephoto lenses are for sports and wildlife photography. Prime high aperture lenses such as a 50mm f1/8 are used portraits. Being able to switch lenses gives the photographer versatility to work in all kinds of situations.

Flash

On most point and shoots, the flash is automatic. With the SLR, the photographer can choose to work with or without flash. Just like lenses, external flashes can be used with the SLR to give more versatile in imagery. Even the new digital SLRs have on-board flash that can be stronger or weaker depending on how the photographer wants to control it. However, most people find that when they can control every aspect of their camera's exposure, they more rarely need to use a flash.

Type of SLRS

Most camera brands makes a SLR. The SLR are a type of camera not a brand of camera. The two most popular brands worldwide are Nikon and Canon, though companies like Sony, Pentax, Minolta and Kodak also make SLRs. SLRs run the gamut in price range: a basic 10 mega pixel Canon SLR can cost as little as $450 and a new professional 22 mega pixel professional Mamiya SLR can cost $6,999.00, as of 2009.
The major differences between these two SLRs (aside from the price) is the speed of the processor, which controls how quickly the camera can snap off shots, and the size of the images it can produce. The biggest difference is the light sensors; the better the sensors, the better the photographer can see in the view finder, and this directly affects how well the photographer can control and tweak her image.