1, the standard lens: in accordance with the traditional theory of photographic optics, Chinese and foreign experts agree that: when the focal length of the lens is equal to the diagonal length of the imaging surface, the lens is called the standard lens. Similarly, when the focal length of the lens is less than the diagonal length of the imaging surface, it is called a wide-angle lens (WIDE) and the focal length is greater than the diagonal length of the imaging surface is called a telescope head (TELE).

(See national standard GB9917-88) Please refer to the following table.

2, measuring length: measuring length and optical total length, the structure of the total length corresponds to the convenience of measuring the choice of lens and the definition, it is the lens barrel (Barrel) top to the PCB surface of the measurement of the size. (See the figure below)

3, lens lens composition concept:

1P lens ------ by a plastic (Plastic) lens composition of the head.

2P lens ------ by two plastic (Plastic) lens composition of the head.

2P2G lens---- a lens composed of two plastic (Plastic) lenses and two glass (Glass) lenses.

4G Lens ------ Lens consisting of four glass (Glass) lenses.

Note: Plastic aspherical lens and glass lens hybrid (Hybrid) lens due to its small image aberration, low cost, is today's world optics trend, a variety of high-grade digital cameras are using this design concept.