What does the camera's lens mean? How to understand
The lens of the camera is a group of lenses, when the parallel light through the lens, will gather to a little, this point is called the focus, focus to the center of the lens distance, called the focal length. Focal length fixed lens, that is, fixed focus lens; focal length can adjust the change of the lens, that is, zoom lens.
When a bundle of parallel light passes through the convex lens with the convex lens of the convex lens, the other side of the convex lens is converged by the convex lens, which is called the focal point, and the focal point to the convex lens center distance is called the focal length of the convex lens. A convex lens has a focal point on each side.
"Focusable range" is the extension of the focal length, usually divided into general shooting distance and close range, the camera's general shooting distance are usually marked as "from a cm to infinity", while the class design products are often also Will provide close-up shooting function (macro), to make up for the general shooting mode can not focus on the problem. Some of the camera is very stressed that with a 1 cm close to support the magic ability, suitable for shooting fine objects.
If you read "f =" in the camera's English specification, then the number followed by the code is usually its focal length, that is, the length of the focal length. Such as "f = 8-24mm, 38-115mm (35mm equivalent)", refers to the length of the camera's focal length of 8-24mm, while the diagonal angle of the equivalent of the traditional 35mm camera 38-115mm focal length. In general, 35mm camera lens lens length is about 28-70mm, so if the focal length is higher than 70mm on behalf of the support for telephoto effect, if less than 28mm said there is wide-angle shooting ability.
The focal length is the measure of the aggregation or divergence of the light in the optical system, which refers to the distance from the center of the lens to the focus of the light gathering. It is also the distance from the center of the lens to the imaging plane of the film or CCD. An optical system with a short focal length has better ability to collect light than a long focal length optical system. Simply say that the focal length is the distance between the focus and the vertex of the mirror.
Heart: the center of the convex lens can be seen as a light heart.
The lens of the camera we use is equivalent to a convex lens, where the film (or the photographic device of the digital camera) is in the vicinity of the focus of the convex lens, or the distance between the film and the convex lens is approximately equal to the focal length of the convex lens.
Convex lens can be imaged, generally with a convex lens to do the lens of the camera, it becomes the most clear as the general will not just fall on the focus, or that the most clear as the distance to the distance (like distance) is generally not equal Focal length, but slightly larger than the focal length. The specific distance is related to the distance between the illuminated object and the lens (object distance), the larger the object distance, the smaller the distance (but in fact it is always greater than the focal length).
Because we are photographed, the distance between the illuminated object and the camera (lens) is not always the same, such as giving a picture, sometimes, like the whole body, away from the body, away from the body, away from the nearest. In other words, the distance is not always fixed, so that in order to get a clear image, it must be different with the object to change the film to the lens of the distance of the heart, the process of change is that we usually say " Coke ".
