dSLR

Digital Single-Lens Reflex (dSLR) cameras use a single lens to project an image through the viewfinder and into the eye using a mirror and pentaprism or pentamirror. When the user activates the shutter, the mirror flips up, temporarily obstructing the view from the viewfinder (blackout) and revealing a pair of shutter curtains behind the mirror which then open and close to expose the sensor for what is typically a pre-determined span of time to provide a properly-exposed image.