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Anonymous users2024-02-11The copy of ls is too annoying, and it doesn't work at all.
In fact, it is very simple, the principal distance: the distance from the node behind the objective lens to the image plane.
Focal length: The distance from an object to the focal plane.
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Anonymous users2024-02-10Focus: The point at which parallel rays of light converge on the optical axis after being refracted through the lens. Focal length f: The distance between the focal point and the center of the lens.
Focus: The point at which parallel rays of light converge on the optical axis after being refracted through the lens. Focal length f:
The distance between the focal point and the center of the lens. Image distance u: the distance between the imaging plane and the center of the lens, its general rule is:
f, the distance between the photographic object and the lens is called the object distance, and the distance between the imaging plate and the lens is called the image distance rather than the focal length.
The concept of focal length
Focal length, also known as focal length, is a measure of the concentration or divergence of light in an optical system, and refers to the distance from the center of the lens to the focal point of light concentration when collimated light is incidence. In a camera, the focal length is the distance from the optical center of the lens to the imaging plane such as the radicle, CCD, or CMOS. The focal length of a camera lens is divided into image-side focal length and object-square focal length.
The focal length of the image square is the distance from the main surface of the image square to the focal point of the image square, and similarly, the focal length of the object side is the distance from the main surface of the object to the focus of the object side. The focal length of a lens determines the size of the image of the subject captured by the lens on the imaging plane.
Assuming that the same subject is shot at the same distance, the longer the focal length of the lens, the greater the magnification of the image on the film or sensor.
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Anonymous users2024-02-09The longer the focal length, the closer the shooting distance, and the brighter the aperture, the stronger the bokeh effect.
The background blur that is loved and frequently used in photography and the focal length and aperture brightness of the lens used (aperture value).
and shooting distance (the distance from the camera to the subject). When the aperture value of the lens used is constant, the longer the focal length, the more likely it is to blur the background. Of course, if the focal length is the same, the lens with a brighter aperture is more likely to produce a bokeh effect.
In addition, the degree of background blur varies depending on the shooting distance. The shorter the shooting distance and the closer you shoot, the greater the bokeh effect. Therefore, if you want to achieve a large bokeh effect, you should choose a lens with a short near-range shooting distance, a brighter aperture, and a longer focal length.
It's just that when you take a photo, you decide on the focal length of the lens first.
After the composition is completed, the shooting distance is fixed, so it is necessary to grasp the relationship between the focal length of the lens and the shooting distance while mastering the basic principle of bokeh that is longer, closer, and brighter.
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Anonymous users2024-02-081. Lens focal length refers to the distance from the principal point to the focal point after the lens optics, which is an important performance indicator of the lens. The length of the focal length of the lens determines the size of the image, the size of the field of view, the depth of field and the perspective strength of the image.
2. 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 imaged on the imaging medium (film, CCD, etc.), which is equivalent to the scale of the object and the image. When shooting at the same target at the same distance, the image with a long focal length is larger, and the image with a short focal length is smaller.
Depending on the application, the focal lengths of camera lenses vary greatly, ranging from a few millimeters to a dozen millimeters to several meters long.
3. The focal length of the lens is divided into image square focal length and object square focal length. The focal length of the image square is the distance from the main surface of the image square to the focal point of the image square, and similarly, the focal length of the object side is the distance from the main surface of the object to the focus of the object side. It is important to note that due to the extensive use of telescope structures in camera lens design, especially in zoom lenses, the focal length of the object and the focal length of the image are not necessarily equal.
When we talk about the focal length of a camera lens, we mean the focal length of the image square.
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The advantage of digital is that it is convenient to save money, but the disadvantage is that it is too convenient, the advantage of film is rigorous, every shot ** must be very careful to press the shutter, otherwise there is no yuan, the disadvantage is to carry a lot of film around, but also to protect the film, there are many types of film, so it is very troublesome!