single-lens reflex

A single-lens reflex camera (SLR) typically uses a mirror and prism system (hence "reflex", from the mirror's reflection) that permits the photographer to view through the lens and see exactly what will be captured, contrary to rangefinder cameras where the image could be significantly different from what will be captured. When the shutter button is pressed the mirror will adjust allowing the light to pass through on to the film, resulting in the image being presented