What does Digital SLR mean

[JamesB]

I am planning to buy a Digital Camera and i have found out some cameras and i would be buying anyone of them Nikon Coolpix P6000, Nikon CoolPix S230, Canon Digital Camera IXUS 870, Canon Powershot A470, KODAK Z980. In all cameras i have found one common feature where each manufacturer has mention it as Digital SLR.Can anyone provide me some information about what is SLR and what are it's features and some important thing about it.

[Bassus]

SLR stands for Single Lens Reflex. SLR cameras permit upright and laterally correct viewing through use of a pentaprism situated in the optical path between the reflex mirror and viewfinder. Light is reflected by a movable mirror upwards into the pentaprism where it is reflected several times until it aligns with the viewfinder. When the shutter is released, the mirror moves out of the light path and the light shines directly onto the film, or in the case of a DSLR, the CCD or CMOS imaging sensor.

[Harshavardhan]

Basic Operation of SLR is as follows:-

1. For viewing purposes, the mirror reflects the light coming through the attached lens upwards at a 90 degree angle.
   
2. It is then reflected twice by the pentaprism, rectifying it for the photographer's eye. During exposure, the mirror assembly swings upward, the aperture narrows (if set smaller than wide open), and a shutter opens, allowing the lens to project light onto the image sensor.
   
3. A second shutter then covers the sensor, marking the end of the exposure, and the mirror lowers while the shutter resets.
   
4. The period that the mirror is flipped up is referred to as "viewfinder blackout". A fast-acting mirror and shutter is preferred so as to not delay an action photo.