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According to the disclosure manual, the experts took you to know the lens of the projector. I believe most friends will feel strange about the lens of the projector, because they have little contact with it, and you will naturally have a question: is the lens of the projector the same as that of the general digital camera, or is there any connection and difference? So I believe this article can increase your understanding in these aspects

in principle, the lenses of digital cameras and projectors are all optical lenses, which use the refraction principle of light and use transparent mirrors. Their essence is the same, which is the similarity between them as the most basic optical devices. However, due to the different application properties and the different effects to be achieved between projectors and cameras, they will show differences in specific detail design and functions:

the first difference is whether there is an aperture. For digital cameras, because the photosensitive range of the photosensitive device (CCD or CMOS) is very narrow, for these devices, it needs a device to control the amount of incident light when the external light exceeds the photosensitive range of the photosensitive device. This is the aperture. It is composed of a group of thin arc metal blades, which are installed in the middle of the lens of the lens. By adjusting the aperture value, the user can make these blades open and close evenly and adjust them into light holes of different sizes to control the light entering the lens to meet different shooting needs. It should be said that as long as it is a camera, it will have an aperture. But at present, most projectors do not have aperture, which controls the luminous flux. However, due to the development of projector technology in recent years, the aperture has also been applied to the lens of the projector. A typical example is the Panasonic pt-ae700 projector, which has just been launched. It uses the "dynamic iris" technology. The "dynamic iris" is an aperture that can expand and contract with the brightness of the projected image. Its purpose is to shrink the aperture when the image is dark in a large area, It reduces the number of rays cast, which improves the contrast of the image. With the progress of the experimental technology of the ty series 10 (5) 0kn liquid crystal material experimental machine, which is mainly applicable to the stretching, peeling, tearing, tightening, zigzag, shearing and other metal and non-metal materials, it is believed that similar aperture technology will add a lot of color to the projector

the second difference is that the zoom ratio is very different: projectors are generally fixed focus lenses. Even for projectors with zoom lenses, the zoom ratio is generally not more than 2, while the zoom ratio of general civil digital cameras is generally more than 3. Only a very small number of digital cameras use fixed focus lenses or lenses with zoom ratios less than 3

the third difference, I believe that friends who have seen digital cameras and projectors know, is the difference in lens aperture: the lens aperture of digital cameras is generally very small, while the lens aperture of projectors is very large. On the one hand, the reason is that the chips (LCD and DLP) of the projector are generally large, which are generally 1.3, 0.9 and 0.7 inches. The lens aperture required to obtain the same aperture is large. The chips (CCD, CMOS) on digital cameras are generally small, usually 1/4 inch. When the same aperture is obtained, the lens aperture required under the initial prestress of 0.7 times the yield strength is small (F value can be simply understood as the ratio of lens focal length to optical lens diameter). In order to obtain the minimum F value (that is, the maximum aperture), it is necessary to increase the lens aperture as much as possible. As a result, the aperture of the projector lens is larger than that of the digital camera. On the other hand, the reason is that the light flux required to meet the internal chips (CCD, CMOS) of the digital camera is small (if not enough, it can also be artificially filled.) The projector needs a large amount of light to meet people's viewing requirements, and there is no way to implement remedial measures when the projector brightness is insufficient! Therefore, in the design of the projector, measures such as the maximum aperture (the minimum aperture value), the maximum lens aperture and the maximum lamp power should be taken to ensure the realization of the minimum brightness value. In the design of the projector, it is not the maximum of the above three parameters, but the best balance between price and performance. This is determined by the current characteristics of industrialized production and businessmen aiming to obtain maximum profits

recognize the aperture F value and focal length f value of the projector

for the lens, in addition to the difference in quality, the most critical parameter is the aperture F value, which is the transmittance of the lens. The larger the aperture f (the smaller the F value), the greater the luminous transmittance of the lens. The aperture of the projector lens is expressed in numerical value, generally from 1 0, the maximum aperture of each lens is marked in front of the lens. What I want to explain here is that the F value of the lens can reach 1.0 in an ideal state. Restricted by the manufacturing process and price factors, the F value can never reach 1.0. For the projector, the lens is the last link in the light path of the projector. The quality of the lens and whether the aperture value can be minimized are directly related to the brightness. The size of the two research projects using functional nanoparticles to make aircraft components conductive is inversely proportional to the F value. The smaller the F value, the larger the aperture

the brightness of the projection image is high. For the fixed focus lens, the aperture value is a constant value. For the zoom lens, through the definition of F value (F value can be simply understood as the ratio of lens focal length to optical lens diameter), we can see that due to the change of focal length, its value is within a range. For example, f2.8-f3.4. The aperture value of a projector is a very important parameter. For example, the same machine uses lenses with different F values, and the brightness difference is very large! For example, the projector of f2.8 is twice the brightness of the projector of F4, four times the brightness of the projector of f5.6, and eight times the brightness of the projector of F8...

as long as their F values are the same, the amount of light they transmit is exactly the same. For example, if two different lenses are f/2.8, the same amount of light will pass through the lens to the screen where the parts do not move relatively. The projector lens is not necessarily large, but its F value is large. It is closely related to the focal length of the lens! It is possible that the F value of a small aperture projector lens is smaller than that of a large lens (the flux is greater)

focal length f is also expressed by numerical value, which is usually divided into short focal length, standard focal length and long focal length, as well as ultra short focal length and ultra long focal length. The smaller the value is, the shorter the focal length is. The larger the value is, the longer the focal length is. The projector's requirements for the lens focal length are generally about 35. The focal length determines the distance between the projector and the screen when the predetermined size is filled. The shorter the focal length, the shorter the projector and the screen

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