Single Lens Reflex camera. In this camera you see what the lens 'sees' by way of a mirror behind the lens directing the light through the lens into a viewfinder. When taking a shot the mirror pops up out of the way and the shutter opens. Often these cameras give you more control over how you want your picture to look. You have control over the shutter speed, exposure and focusing which means that you can be very creative with your photography.