What is focal length infinity ?

1. Focal length, also known as focal length, is a measure of the concentration or divergence of light in an optical system, which refers to the distance from the center of the lens to the focal point of light concentration. It is also the distance from the optical center of the lens to the imaging plane such as the tintle or CCD or CMOS in a camera. Optical systems with short focal lengths have a better ability to concentrate light than those with long focal lengths.

Second, generally we say: focal length is the distance from the center of the lens to the focal point. However, this is only the case of a single thin lens, and since the lens of a camera is made up of many lenses, the situation is far from simple.

Third, 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.

Fourth, when the photographic lens is adjusted to infinity, it is actually a nominal focal length. In the design, the distance between the main plane of the lens and the film or imaging sensor is adjusted to the length of the focal length, and then the image away from the lens can be formed on the film or sensor to form a clear image. When the lens is going to shoot a relatively close object, it is the actual focal length of the lens that is changed.

Focal lengths are usually marked in millimeters (mm), but it is still possible to see some older lenses that use centimeters (cm) or inches. The size of the field of view depends on the ratio of the focal length of the lens to the size of the negative. Since the most popular is the 35mm format, the field of view of the lens is often marked according to this specification.

The field of view is different for standard lenses (50mm), wide-angle lenses (24mm), and telephoto lenses (500mm). The same is true for digital cameras, where the sensor is smaller than conventional 35mm films, so the same image can be obtained with a shorter focal length.

Super focal length refers to the infinite focus, the clear point closest to the lens in the clear range is called super focus, and the unclear range between the super focus and the lens is called super focal length, by confirming and using the super focal length, we can increase the original depth of field range in shooting, very simple, as long as the lens focus is on the super focus instead of infinity, you can do it. The determination of the superfocus can be based on the depth of field table on the lens, first adjust the focus to infinity, and then refer to the depth of field table according to the selected aperture to determine the nearest sharp point of the depth of field range, which is the superfocus, and then focus on the superfocus. Suppose the infinity object is 100 meters away from the lens, if the infinity is focused, the clear range is 80 meters to 100 meters, we change the focus to 80 meters, then the sharp range will become from 60 meters to 100 meters, and the clear range is greatly increased.

When you photograph a distant object (for example, 10 meters away, depending on the lens), the focal length of the camera is infinitely far away, and the object can be photographed very clearly in a large range. All lenses only have the closest distance that can be illuminated (for example, a macro of 3mm, which means that the closest distance that can be illuminated is 3mm), there is no maximum distance, and all cameras can adjust the focal length to infinity. The infinity of the manual camera is indicated by an infinitely looping symbol whenever you want to shoot a distant scenery or even a portrait, you can adjust the focus to infinity.

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 incident [1]. Optical systems with short focal lengths have a better ability to concentrate optical blind bonds than optical height systems with long focal lengths. In simple terms, focal length is the distance between the focal point and the center point of the mask.

The focal length of the camera is f, and the image distance < 2f can be imaged.

Chinese name. Focal length.

Alias. Focus length.

Conception. A measure of how light gathers or diverges.

Essence. The distance from the center of the lens to the imaging plane of the subsurface.

Formula. c^2=a^2-b^2

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.

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 square focal point, fast reading distance 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 the lens determines the size of the image 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 formed by the subject on the film or image sensor.

Focal length is the distance from the center of the lens to the focal point of light concentration when collimated light is incidence.

Focal length is a measure of the concentration or divergence of light in an optical system, which refers to the distance from the center of the lens to the focal point of light concentration when collimated light is incidentified. Optical systems with short focal lengths have a better ability to concentrate light than those with long focal lengths, which is simply the distance between the focal point and the center point of the mirror.

Focal length, also known as focal length, is the distance in a camera from the optical center of the lens to the imaging plane such as the Mirror, CCD, or CMOS, and optical systems with short focal lengths have a better ability to concentrate light than those with long focal lengths. For a thin lens in air, the focal length is the distance from the center of the lens to the main focal point, and for a converging lens, the focal length is positive.

Lens focal length:

Generally speaking, focal length is the distance from the center of the lens to the focal point, but this is only the case of a single thin lens, because the lens of a camera is composed of many lenses. Therefore, the situation is far from simple, the focal length of the lens is divided into image square focal length and object square focal length, and the image square focal length is the distance from the main surface of the image square to the focal point of the image square.

Similarly, the object focal length is the distance from the main surface of the object to the object focus. It must be noted that due to the design of camera lenses, especially the extensive use of telescope structures in zoom lenses, the focal length of the object side is not necessarily equal to the focal length of the image side, and the focal length of the camera lens we usually refer to as the image side focal length. For example, for an 8mm fisheye lens, the image square principal plane should be located 8mm directly in front of the focal plane.

Wireless focus means that the focus is at infinity.

There are three elements that affect the depth of field, first, the distance between the photographer and the subject, that is, the distance between the camera and the focal point, the second, is the problem of focal length, the focal length is long, the depth of field is small, the focal length is short, the depth of field is large, and the third is the problem of aperture, the aperture is large, the depth of field is small, and the aperture is small and the depth of field is large.

If you want to shoot clearly, try to use a small aperture, and the smallest focal length, and most importantly, where you put the focus, it is impossible for you to make the whole landscape picture clear before and after! There is only one focal point, and it may be relatively clear in other places, but only the focus is the clearest.

That is, the focus point is at infinity, but not the maximum depth of field.

If you want to cover the maximum range, set it according to the aperture selected"Superfocus distance"That's right.

The aperture is the smallest, and the depth of field is the largest.

Focal length is a measure of the concentration or divergence of light in an optical system, which refers to the distance from the center of light of a lens to the focal point of light concentration.

In simple terms, focal length is the distance between the focal point and the apex of the mirror.

The lens of the camera is a set of lenses, when the light rays parallel to the main optical axis pass through the lens, they will converge to a point, this point is called the focal point, and the distance from the focus to the center of the lens is called the focal length.