【 Weak current College 】 projector lens detailed

Believe that most users for projector lens will feel strange, because fewer contacts, and you will naturally have a doubt, that is the projector's lens and General digital camera lens is not the same, or have any contact with you believe this article? in these areas can increase your awareness.
From theory, digital camera, projector's lens is a lens that is using the light refraction principles are used to light microscopy, their essence is the same, this is both as one of the most basic optics sense of similarities. But because of the projector and the camera application between different nature as well as to achieve the effect is different, so they each be in specific details on the design and function to demonstrate the differences:
The first difference is that there is no aperture this device. For digital cameras, photographic devices (CCD or CMOS) by photosensitivity range is very narrow, so for these devices, it needs a light in the outside world than photosensitive devices in the PC range control number of the incident light device, this is the aperture, it consists of a series of very thin arc type Metal Blade, they are installed in the camera's lens. The user can adjust the aperture value, you can make these leaves evenly into retractable, adjust the size of different optical bore control into the lens light to accommodate different photography needs. It should be said that as long as the camera will have aperture. But in the meantime most of the projector does not stop the control light flux number of devices. However, because of the recent years projector technology, aperture are also applicable to the projector's lens, more typical of a recently launched near Panasonic PT-AE700 projector, using a dynamic IRIS "technology", the "dynamic IRIS" is the one with the projection image brightness and expansion, contraction of aperture, its purpose is to image appears large dark, shrink the shadows in Aperture, light doubly reduced, thus improving the contrast of the image. As technology advances, to believe that similar aperture technology makes the projector.
The second difference is the zoom ratio of the difference is very large: the projector lens is up, even the zoom lens of the projector, the zoom ratio is not greater than 2 in General, and general civil level digital camera zoom ratio is generally 3 above, only a very small number of digital camera with fixed focus lens or zoom lens ratio less than 3.
The third difference between believe seen digital camera and projector friends all know, that is the lens aperture: digital camera lens aperture is very small, but the projector's lens aperture is huge. One reason is because the chip projectors (LCD, DLP) generally are relatively large, typically 1.3, 0.9, 0.7 ", at the same aperture of the lens aperture is big. While digital cameras on the chip (CCD, CMOS) generally smaller, typically 1/4 inch, the same aperture of the lens aperture is small (f value can be simply understood as the lens and the optical lens diameter ratio). In order to obtain the smallest f value (that is, maximum aperture), it is necessary to intensify the lens aperture as possible. This caused the projector lens diameter relative to digital camera aperture is relatively large. On the other hand was satisfy internal chips for digital cameras (CCD, CMOS) the desired flux less (not enough, artificial light. ) And projector in meet people watch requirements need a large quantity of light, and projector brightness is insufficient, it is impossible to implement remedial measures! so projector in the design-time use maximum aperture (the smallest aperture value), the maximum lens aperture, maximum lamp power and other measures to guarantee the minimum brightness value realization, in projector design time, and not on these three parameters are take maximum, but in price and performance for an optimal balance. This is now industrialized production, businessmen to get maximum profit for the purpose of the decision.
Recognizing the value of the projector aperture and focal length f F value
For the lens, in addition to quality differences, the most important parameter is the size of the aperture value f, where f is the lens light rate. The larger the aperture f (the smaller the f value), the camera's light, the greater the rate. Projector lens aperture is represented with numeric values, generally from 1.6-4.0, each lens of maximum aperture is used before the lens numerically. Here to tell you is that the lens f value on the ideals of the State can achieve the value of 1.0, manufacturing process, price factors, and other constraints, the f value is never do 1.0.
For projectors, optical projector lens is the last link, lens to do good or bad, aperture value will be the smallest, and brightness is directly related to the size of the aperture and the f values inversely, the smaller the f value, the larger the aperture. The brightness of the projected image is high, for focusing lens, the aperture value is a constant value, for a zoom lens, the definition of value through f (f value can be simply understood as the lens and the optical lens diameter ratio) we can see that the changes due to focal length, its value is in a range. For example, f2.8-f3.4. Projector aperture value is a very important parameter, for example, the same machine, use the f value different lens, its brightness difference is very large! such as f2.8 projector is f4 projector brightness is diploid, f5.6 projector brightness with four times the f8 projector brightness of eight times ...
No two just lens, as long as they are the same as the value of f, then they transferred the amount of light is exactly the same. For example, two different lenses are f/2.8, then you will have the same amount of light reaching the screen through the lens. Not necessarily projector lens, its f value, it is and the lens has a close relation! likely a diameter small projector lens f value than large lens f value but also small, (greater amount of light).
Focal length F is also represented with numeric values, usually from 50-210, divided into short focal, standards and telephoto, short and long-focus. Number, the shorter the small focal length, the higher the value, the longer the focal lengthThe projector on lens requirements are cast in general 50-140, rear projection, at around 35 General focus determines when playing full intended dimensions and shadow projector screens of the shorter distance, focal length, projector and shadow, the greater the distance from the screen, on the contrary it farther. If you are a short distance projection big screen you need to select short focal lens of the projector, instead you need to select a telephoto lens. General projector for standard lens.
Actual use how to choose the right lens F value
Lens focal length determines whether the lens in the projector and screen distance under certain conditions to form the image size. The shorter the focal length of the lens, the projection of images on the screen.
The choice of the projector, the application of the General, in the same price, selection criteria should be given priority, standard lens in the projected image in color reproduction, image distortion is the best application for narrow!, to a large size of the projected images, should give priority to the use of short focal lens (of course, conditions permitting, can also be taken into account in the standard lens projector using optical refraction method for large-size projection image. Application for leniency), in the case of funds, give priority to the telephoto lens, because this way, the advantages are many, first of all, the projector's fan noise in the viewer's influence was very good, and secondly in the viewer's influence on the projector (smokers ash, Diner food residue, hot steam) factors, the impact of long focal projector is the smallest! this also as the projector creates a comfortable working environment, to facilitate the operation of the projector's longevity.
For aperture value, there is no choice, but we choose projector, through controlled different projector aperture value, you can know the power of this projector product utilization for different aperture value, but the same brightness projectors, aperture value (aperture) of projectors, the lamp power must be less than the aperture value big projectors. It is energy conservation.
Tidbits: high-end large projector different brands is generally based on the size of the different image size and projection distance and replace the lens. According to the different needs of General interchangeable lens to: shortening the projection distance and application for wide angle lenses, to shorten the distance between the rear-projection and application of rear projection, to lengthen the wide angle mirror projection distance and the telephoto lens is applied. These focal length lens replacement is very convenient, as a general rule, operations personnel in does not require any tools in just 1-2 minutes to complete.
Epilogue
World, except for a small digital camera, projector manufacturers ourselves to the development of the projector lens, most projectors manufacturers for the lens portion (optical components) approach is to purchase a lens manufacturer in the production of finished product. Now, the world's most advanced glass processing technique is optical glass lens molding technology, it is a high-precision optical components machining technology, is the softening of glass in the high-precision molds, heating compression and anaerobic conditions, one-time direct compression molding out reach requirements of optical parts. The world has mastered the advanced glass optical parts manufacturing technology of well-known companies and small manufacturers, the only United States Kodak, Corning Corporation, Japan's largest original, Hoya, OU Linbasi, Panasonic Corporation, the Zeiss company in Germany and the Netherlands of Philips company able to produce large quantities of industrialization.