For a projector, the projector lens is the last link in the projector's optical path. Whether the lens is good or not, and whether the aperture value can be minimized are directly related to the brightness. The size of the aperture is inversely proportional to the f value. The smaller the f-number and the larger the aperture, the higher the brightness of the projected image. For a fixed-focus lens, the aperture value is a constant value. For a zoom lens, through the definition of the f-number, we can see that its value is within a range due to the change of the focal length.
Any two lenses, as long as they have the same f-number, will transmit exactly the same amount of light. So it doesn't necessarily mean that the projector lens is large, and its f value is large, which is closely related to the focal length of the lens. It is possible that the f value of a projector lens with a small aperture is smaller than that of a large lens (larger light transmission).
For the aperture value, there is no room for choice, but when you choose a projector, you can know the power utilization rate of the determined projector product by comparing the aperture value of different projectors. For projector products with different aperture values but the same brightness, the projector product with a large aperture value must have a lamp power smaller than that of a projector product with a large aperture value. If you want to project a large picture in a short distance, you need to choose a projector with a short-focus lens, otherwise you need to choose a long-focus lens. General projector lenses are standard lenses.
The focal length of the projector lens determines the size of the image that the lens can form under the condition of a certain distance between the projector and the screen. The shorter the focal length of the lens, the larger the image projected on the screen.
In the selection of projectors, in general application places, at the same price, the standard projector lens should be selected first. The standard lens is the best in the restoration of the projected image and the geometric distortion of the image! For a narrow application space, if you want to project a large-scale image, you should give priority to using a short-focus lens. For large application places, when the funds are sufficient, the telephoto lens is given priority, because such an installation method has many advantages. First, the noise of the projector is well suppressed from the impact on the viewer. Among the factors affecting the projector by the viewer (smoker's ash, diner's food crumbs, hot drink steam), the influence of the telephoto projector is the smallest! This also creates a comfortable working environment for the projector and facilitates the longevity of the projector.