First, the lenses of different bayonet cars are not necessarily universal. Some bayonets can be used through the adapter ring, but in general, the lens of an SLR car can be used on a micro single, and the lens of a full-frame system car can be used on an APS-C or M43 format, otherwise can. The lens of the car should be the same as far as possible, which can improve the versatility of the car DVR lens of different specifications in the later stage. It mainly refers to the lens of the car is divided into the lens of the full-frame car and the lens of the APS-C car. For example, Canon SLR lenses include EF lenses (full-frame) and EF-S lenses (APS-C). The full-frame car lens can be used in the APS-C body. Otherwise, it can be successfully installed and cannot be used normally. So when we buy a car lens, we always say that buying a full-frame car lens can reduce the trouble of replacing the car lens in the future, because the lens of the APS-C car cannot fit the full-frame lens.