The difference between full-frame camera and medium-frame camera.

The full picture is relative to the 35mm film camera, which is called 135 film camera. The medium format you mentioned is APS technology, which was originally thought to be an "advanced photography system". It is different 35mm the specifications of a new generation of photographic systems introduced by 1996 Kodak, Fuji, Canon, Minolta and Nikon. This is a film system product, which uses some digital technologies.

However, major manufacturers have invested a lot of manpower and material resources in the research and development of APS products, so they have launched a large number of products in this format in SLR digital cameras, so that their huge investment more than ten years ago has not been in vain.

The size of Quan Huafu is about 36×24mm, while the frame of APS system is about16.7× 30.2 mm. The focal length conversion ratio of the two cameras in lens use is 1.5 times, that is, if the lens of traditional 35mm system (Quan Huafu) is used on APS, its focal length value needs to be multiplied by 1.5. For example, the traditional 24mm lens will become a lens with a focal length of 36mm in the medium format system.

It should be noted that the lens designed for Quan Huafu system can be used in a medium-format camera to obtain an image of Quan Huafu, but the lens specially designed for a medium-format camera cannot be used in a full-frame camera, otherwise the picture it shoots will not be full of photosensitive devices, and it looks like there is a black circle around it.