What does SLR af mf mean?

AF and MF on the lens mean automatic and manual switching, mainly depending on whether the photographer is used to manual focusing or automatic focusing when taking pictures. AF stands for auto focus, and the camera automatically controls the lens focus. MF stands for manual focusing, that is, the user turns the focus ring by his own feeling to focus.

In the digital camera system, after the light reaches the reflector through the lens, it is refracted to the focusing screen above to form an image. Through the eyepiece and pentaprism, we can see the scenery outside in the observation window. In contrast, ordinary digital cameras can only see the captured images through the LCD screen or electronic viewfinder (EVF). Obviously, the directly seen image is more conducive to shooting than the processed image.

When shooting in DSLR, press the shutter button, the reflector will pop up, and the shutter curtain in front of the photosensitive element (CCD or CMOS) will be opened at the same time, and the light passing through the lens will be projected onto the photosensitive original, and then the rear reflector will be restored immediately, and the image can be seen in the viewfinder. This structure of the single-lens reflex camera ensures that it is shot through the lens, so that the image seen in the viewfinder is always consistent with the image on the film, and its framing range is basically consistent with the actual shooting range, which is very conducive to intuitive framing and composition.