What does the lens 50mm mean?
According to the length of the focal length of the lens, that is, when shooting perspective, can be divided into standard lens, wide-angle lens and long focal length lens.
The standard lens angle of about 50 degrees, which is the human monocular head and eyes do not turn the case can see the perspective, from the standard lens to observe the feeling and we usually see the same scene. 35mm camera standard lens focal length of 40mm, 50mm or 55mm. 120 camera standard lens focal length is generally 80mm or 75mm, the larger the camera frame, the larger the focal length of the standard lens. The digital camera because of its imaging medium (CCD or CMOS) is very small, the standard lens focal length is not consistent. In order to facilitate the sense of straight, talking about the DC lens is often used when the equivalent of 35mm camera equivalent focal length, the equivalent refers to the equivalent of the angle of view. The following only said 35mm camera lens, other film cameras and digital cameras can be analogy.
ou said this refers to the lens focal length, because the lens focal length is the basic knowledge of photography, although very simple, but let you from the theory to the actual understanding or need to say a lot, give you find some information to see:
Lens focal length: refers to the lens after the main point of the optical distance to the focus of the lens is an important performance indicators. The length of the focal length of the lens determines the size of the image, the angle of the field, the depth of field and the perspective of the screen.
The focal length of the lens is a very important indicator of the lens. The length of the focal length of the lens determines the size of the subject on the imaging medium (film or CCD, etc.), which is equivalent to the scale of objects and images. When shooting the same subject with the same distance, the image of the lens focal length is large, and the image of the lens is short. According to the different uses, the camera lens focal length difference is very large, there are short to a few millimeters, more than ten millimeters, there are up to a few meters. More common are 8mm, 15mm, 24mm, 28mm, 35mm, 50mm, 85mm, 105mm, 135mm, 200mm, 400mm, 600mm, 1200mm, as well as up to 2500mm long telephoto telephoto lens.
What is the definition of lens focal length? In general we say: focal length is the lens is the center to the focus of the distance. But this is only a single film thin lens situation, because the camera lens is composed of a number of lens combination, therefore, the situation is far from simple.
Long focal length lens is suitable for shooting long distance scene, depth of field is small, so easy to make the background blurred, the main prominent. 35mm camera long focal length lens is usually divided into three, 135mm below the middle of the focal length, such as 85mm, viewing angle 28 degrees, 105mm, viewing angle of 23 degrees and 135mm, viewing angle of 18 degrees. Medium focal length lens is often used to shoot portraits, sometimes called portrait cameras. 135-500 called long focal length, such as 200mm, viewing angle of 12 degrees, 400mm, viewing angle of 6 degrees. 500mm or more known as the long focal length, the viewing angle of less than 5 degrees, suitable for shooting distant scenes. Such as the close-up on the pitch and the shooting of wild animals, because not close to the subject, long focal length lens is very useful.
Wide-angle lens, as the name suggests is its photographic perspective is relatively wide, suitable for shooting distance and range of large scenery, sometimes used to deliberately exaggerate the prospects for performance, strong sense of distance and perspective. 35mm camera typical wide-angle lens for the focal length of 28mm, viewing angle of 72 degrees. Commonly there are slightly longer than the 28mm 35mm, 38mm so-called small wide angle (more common in fool machine).
Wider than the general wide-angle lens is ultra wide-angle lens (such as focal length of 24mm, viewing angle of 84 degrees) and the so-called fisheye lens, the focal length of 8mm, viewing angle of up to 180 degrees.
