What does "SLR residual amplitude" mean?

Refers to APS-C frame, and the photosensitive element is smaller than Quan Huafu, which is also called "half frame". Because its image is essentially equivalent to cutting a piece in the middle of the whole picture, it is also called "editing".

SLR residual focus matching: As long as the bayonet matches, any fixed-focus lens can match half a SLR. As long as we pay attention to the focal length conversion coefficient of 1.5 times or 1.6 times when choosing, we can avoid the situation that the space is narrow and the focal length is too long to play.

Residual frame refers to APS-C frame, which was originally born in the film era. Its original intention is an advanced camera system. 1996, Kodak, Fuji, Canon, Minolta and Nikon introduced the specifications of a new generation of photo systems different from the 35mm film system.

Digital SLR camera is a single lens reflex digital camera, referred to as SLR (single lens reflex). This technology is to install a mirror at a 45 angle in front of the film plane, and there are frosted glass and pentaprism eyepiece above the mirror in turn. The pentaprism reflects the real image light many times to change the optical path, and sends the image to the eyepiece, so that the image seen in the observation window is always consistent with the image on the film, and the shooting range is basically the same as the actual shooting range. The unique design of this prism enables the photographer to directly observe the image passing through the lens from the viewfinder.