Digital Camera terminology

Optical zoom:

Optical zoom occurs when the positions of the lens, object, and focus change. When the imaging surface is moving horizontally, for example, the visual and focal length will change, and the farther scenes will become clearer, making people feel like objects are moving forward. Therefore, changing the focal length of a lens is optical zoom.

An optical zoom multiple is the ratio of the maximum focal length to the minimum focal length that a zoom lens can achieve. For example, the parameter of a zoom lens is 18-200, which means that the minimum focal length of the lens is 18mm, the maximum focal length is 200mm, and the zoom factor is 200/18 = 11.11 times. This parameter only indicates that the zoom range of the lens is large. It does not indicate how long the focal length is. For example, if the parameter of a single lens is 300-600, the zoom factor is 600/300 = 2 and only 2 times the optical zoom. However, the focal length of the latter is much larger than that of the former, with good remote camera capabilities, it can basically be regarded as a camera. Therefore, the maximum focal length is used instead of the magnification.

Therefore, there is no comparability between 12, 15, and 18 times of optical zoom. If you want to enlarge the number of BB in the lens parameter AA-BB, the larger the better. If you don't want to take a distant object, you should select smaller ones, so that the imaging quality is better. So you can choose a camera that requires several times of zoom.

For a zoom lens of 10 times or more, it is rare to have a few good imaging lenses (relatively speaking). It is difficult to guarantee the precision of a zoom lens to achieve a zoom of 10 times or more, this is why large zoom lens imaging in a single lens is not ideal and the price is average. A rich photographer does not want to have a head of 18-200, but is willing to have two heads to cover this focal segment, such as 18-55, 70-, and two heads, so that the imaging quality is good.

 

Telefocus:

The telefocus refers to the distance that the lens can reach. For example, 10 times is the distance from the lens to 35mm, which is convenient for capturing distant scenes. Short Focus generally refers to near focus or micro distance, that is, scenes close to the camera can be photographed. Generally, the text in the book is used. Focusing is to focus and make the scenes clearer on the camera or display screen.

Generally, a lens with a focal length greater than 135mm is called a focal length.

Wide angle:

 

The biggest feature of wide angle is that it can be shot in a wide range, with the characteristics of exaggerating the sense of distance, wide focus range, and so on. When the wide angle is used, the objects in front of the eyes can be placed larger, and objects in the distance can be reduced smaller. The surrounding images are easy to be distorted, which is also a major feature of the system. The wide angle can also adjust any point in the image to the most appropriate focal length, making the image clearer, or completely auto focus.

A wide-angle digital camera has a short focal length, wide angle, and deep depth of field. It is suitable for taking photos of large scenes, such as buildings and scenery.

The real wide-angle digital camera is actually a product with a focal length of 28mm wide angle. Because the 28mm Wide Angle field of view is wider than the most common 35mm and 38mm Wide Angle on a digital camera, the 28mm Wide Angle field of view is a 76 degree angle of view, and the 35mm is only 62 degrees, therefore, it can produce unique visual effects to accommodate a wider range of scenarios.

 

Aperture:

An aperture is a device used to control the amount of light that passes through the lens and enters the photosensitive surface of the body. It is usually within the lens. F is used to express the aperture size. It is impossible for us to change the diameter of a manufactured lens at will, but we can add a polygon or circular inside the lens and a variable aperture grating to control the amount of light passing through the lens, this device is called aperture.

Aperture f = focal length of the lens/diameter of the lens diameter

From the above formula, we can see that to reach the same aperture F value, the aperture of the long focal length lens is larger than that of the short focal length lens. The complete optical circle value series are as follows:

F1, f1.4, F2, f2.8, F4, f5.6, F8, F11, F16, f22, f32, f44, f64

It is worth mentioning that the smaller the F value of the aperture, the more incoming light in the same unit of time, and the more incoming light in the upper level, the more than twice the next level, for example, when the aperture is adjusted from F8 to f5.6, the Light Input volume is doubled. We also say that the aperture is increased by a level.

The English name of the aperture is aperture. the aperture is a device used to control the amount of light that passes through the lens and enters the photosensitive surface of the fuselage. It is also an extremely important indicator parameter of the camera, which is usually within the lens. Its size determines the amount of light that enters the photosensitive element through the lens. F is used to express the aperture size. Aperture f = focal length of the lens/diameter of the lens diameter from the above formula we can see that to reach the same aperture F value, the aperture of the long focal length lens is larger than that of the short focal length lens.