Reflex camera

Cross-section view of an SLR system, one of several systems by which reflex cameras are able to operate: 1: Front-mount lens (four-element Tessar design) 2: Reflex mirror at 45-degree angle 3: Focal plane shutter 4: Film or sensor 5: Focusing screen 6: Condenser lens 7: Optical glass pentaprism (or pentamirror) 8: Eyepiece (can have diopter correction ability)

A reflex camera is a camera that permits the photographer to view the image that will be seen through the lens, and therefore to see exactly what will be captured, contrary to viewfinder cameras where the image could be significantly different from what will be captured. A single-lens reflex camera typically uses a mirror and prism system (hence "reflex", from the mirror's reflection) to accomplish this. The mirrorless interchangeable-lens camera achieves the same result by providing the photographer with a digitally captured image. The twin-lens reflex camera provides both a viewfinder image and the reflected image from the actual camera lens.