What are the moons and stars captured by the 50mm SLR lens?

SLR cameras (SLR cameras) are also called SLR cameras. Refers to a camera that uses a single lens, through which light shines on the reflector and takes a view through reflection.

The so-called "single lens" means that the photographic exposure light path and the framing light path * * * use one lens, unlike the paraxial camera or the double-reflex camera, the framing light path has an independent lens. "Reflection" means that a plane mirror in the camera separates the two light paths: when the mirror falls during framing, it reflects the light of the lens to the pentaprism and then to the framing window; When shooting, lift the reflector quickly, and the light can shine on the film or photosensitive element CMOS or CCD.

In this system, the unique design of the mirror and prism enables the photographer to directly observe the image passing through the lens from the viewfinder.

It can be seen from the structural diagram of a single-lens reflex camera that the light reaches the reflector through the lens and is reflected to the focusing screen above to form an image. Through the eyepiece and pentaprism, we can see the scenery outside in the observation window. ?

The light passes through the lens and is reflected by the reflector to the frosted viewfinder. Through the convex lens and reflected in the pentaprism, the final image appears in the viewfinder. When the shutter is pressed, the mirror moves in the direction shown by the arrow, and the mirror is lifted, and the image is taken on CCD or CMOS, which is consistent with what is seen on the viewfinder screen.