Camera or video camera?

Aperture value is a relative value (reciprocal of relative aperture) obtained from lens focal length/lens diameter.

First, the quantifier unit of camera is: a camera, a camera, a camera. Camera is generally used as a name inherited from the past, because the camera was relatively large when it first appeared, and it is more appropriate to use "one" as a quantifier unit. Nowadays, the camera is small and exquisite, beautiful and fashionable, and it is more appropriate to call it "one".

2. Introduction to the camera: A camera is also a camera. It is a kind of equipment that uses the principle of optical imaging to form images and records images with negatives. This is an optical instrument used for photography. In modern social life, there are many devices that can record images, all of which have the characteristics of cameras, such as medical imaging equipment and astronomical observation equipment.

3. For a 50mm standard lens, the maximum light flux diameter is 29.5mm, and the calculated maximum aperture is 50mm÷29.5mm=F 1.7, so it can be understood that although the maximum light flux diameter is the same, the maximum aperture of the same zoom lens is different under different focal lengths. The larger the f value, the smaller the aperture. Conversely, the smaller the f value, the larger the aperture.