What does the SLR in the camera mean?

SLR in a camera refers to a Single Lens Reflex Camera (SLR camera). It refers to a camera that uses a single lens, and the light shines on the reflector through this lens, and takes a view through reflection.

"single lens" means that the photographic exposure light path and the framing light path * * * use a single lens, unlike a paraxial camera or a double-mirror camera, where the framing light path has an independent lens.

"reflection" means that a plane reflector in the camera separates the two light paths: the reflector falls when taking a view, reflecting the light of the lens to the pentaprism and then to the viewing window; When shooting, the reflector is lifted quickly, and the light can shine on the film or the photosensitive element CMOS or CCD.

Extended information:

Features of SLR camera:

1. It has only one lens, which is used for both shooting and framing, so the parallax problem is basically solved. When taking a view, the light from the object is focused by the lens, reflected by the oblique reflector to form an image, and then reflected by the "roof prism" ridged at the top. The scene can be observed through the eyepiece, and it is the same image as the scene, so it is very convenient to take a view and focus.

2. A single-lens reflex camera can be replaced with various matching wide-angle, medium-focus, telephoto or zoom lenses at will, and a close-up lens, an extension ring or a telescopic leather cavity can be installed on the lens as required. In short, any scene that can be seen clearly from the viewfinder can be photographed by the camera.

3. A simple single-lens reflex camera using 12 film generally does not need a pentaprism (such as the Great Wall DF-4), and can directly view and focus on the ground glass; Middle and high-end single-lens reflex cameras can also be replaced by overlooking viewfinder, which is one of the reasons why single-lens reflex cameras gradually replace double-lens reflex cameras.

reference source: Baidu Encyclopedia-SLR camera