What are full frame and half frame?

The definitions of full-frame and half-frame are as follows:

Full-frame: Full-frame (or full-frame, 135 full-frame) is a photography term, referring to the photosensitive The size is 36×24mm. This specification is used to describe the image circle index of the lens and the size of the sensor element.

Half-frame: Half-frame means that the camera sensor is approximately half the size of full-frame. Sensors of this size are often called APS-C format. Due to their smaller sensor size, half-frame cameras usually have smaller volume, lighter weight, and lower manufacturing costs. In terms of imaging quality and visual effects, half-frame cameras are not as good as full-frame cameras, but in some cases It can still provide good enough performance, especially when shooting landscapes, portraits and other subjects.