Photographic terminology

◎ Exposure bàoguāng

[Exposure] To expose photosensitive paper or photographic film.

◎ Exposure pü gu ā ng

[Exposure] Sensitivity of photographic photosensitive materials

expose

1. Make photographic film or photosensitive paper sensitive under certain conditions. After exposure, a latent image is formed, and after cleaning and processing, a visible image is presented.

2. It means that something is exposed or exposed. Jiefang Daily 1988.7.26: "Most of these people have an unsafe mentality, because their love foundation is not solid, and they are afraid that the other person's interest will shift with time, they will have another love, or some of their shortcomings will gradually be' exposed'."

3. Metaphor refers to people who appear in public. The love story of Shen Xicheng, a famous Hong Kong writer: "He wrote letters to readers, sent photos, signed autographs, appeared on TV, gave interviews and even participated in film performances, which can be said to be as exposed as possible." Jiefang Daily 1988.5.6: "Gambling is not a glorious thing after all, so it is not surprising that gamblers are afraid of being exposed."

Exposure p guāng

The physical meaning of exposure means that light forms a latent image on the photosensitive layer (coated with photochemical substances). The process after exposure is chemical development, which makes the latent image appear and solidify.

Many devices in industry apply the exposure principle to transfer graphic signals to the required materials.

Camera and equipment with shutter: By opening the shutter, different bright and dark light makes the images of people, scenery and objects exposed on silver salt film to produce latent images.

Laser imagesetter (photo-plotter): converts the electrical signals of electronic documents made in the computer into optical signals, and exposes them on the film by scanning line by line, so that the film produces latent images.

Print printer: the film with pictures and texts and the plate coated with photosensitive substances are stacked together, and the lights of the equipment are lit-exposed, and the pictures on the film produce latent images on the plate.

Brown exposure machine: the picture on the film is photocopied on the brown film (diazo film) by exposure.

Screen exposure machine: also known as screen printing machine, it exposes the pictures on the film to the screen coated with photosensitive materials.

Circuit board exposure machine: expose the picture on brown film (diazo film) to the hard PCB or soft FPC of the circuit board coated with photosensitive material or photosensitive dry film.

Exposure mode

The English name of Exposure is exposure, and the exposure mode is the mode that the computer uses natural light source, which is usually divided into various modes, including shutter priority, aperture priority, manual exposure, AE lock and so on. The quality of the photo is related to the exposure, that is, how much light is needed to make the CCD get a clear image. Exposure is related to light passing time (determined by shutter speed) and light passing area (determined by aperture size).

Shutter and aperture take precedence:

In order to get the right exposure, you need the right combination of shutter and aperture. When the shutter is fast, the aperture will be larger; The aperture is smaller when the shutter is slow. Shutter priority means that the exposure value is calculated by the automatic metering system of the machine, and then the aperture is automatically determined according to the shutter speed you choose. Aperture priority means that the exposure value is calculated by the automatic metering system of the machine, and then the number of shutters is automatically determined according to the aperture size you choose. When shooting, users should balance the exposure and shutter according to the actual environment, which complement each other.

The larger the aperture, the more light passes through per unit time, and vice versa. Aperture is generally expressed as the letter "F+ value", such as F5.6, F4, etc. It should be noted that the smaller the value, the larger the aperture. For example, F4 is larger than the aperture of F5.6, and the difference between two adjacent apertures is twice, which means F4 is twice as big as that passing through F5.6. Relatively speaking, the definition of shutter is very simple, that is, the time allowed for light to pass through the aperture is expressed by numerical values, such as 1/30 seconds, 1/60 seconds, etc. Similarly, the difference between two adjacent shutters is twice.

The combination of aperture and shutter forms exposure, which is not unique under certain exposure conditions. For example, the current normal exposure combination is F5.6 and 1/30 seconds. If the aperture is increased by one step, that is F4, the shutter value at this time will become 1/60, and this combination can also achieve normal exposure. Although different combinations can achieve the same exposure, the pictures taken have different effects.

Shutter priority is to get the aperture value through camera metering when the shutter is defined manually. For example, shutter priority is mostly used to shoot moving objects, especially sports shooting. Many friends find that when shooting moving objects, the subject is often blurred, mostly because the shutter speed is not fast enough. In this case, you can use the shutter priority mode, roughly determine a shutter value, and then shoot. Because the shutter is fast, the amount of light entering may be reduced and the color is light, so it is necessary to increase the exposure to enhance the brightness of the picture. The motion of the object is generally regular, so the shutter value can also be roughly estimated. For example, when shooting pedestrians, the shutter speed is almost1125 seconds, while it takes11000 seconds to shoot falling water droplets.

Manual exposure mode:

Manual exposure mode requires manual adjustment of aperture and shutter speed every time shooting, which is beneficial for photographers to create different picture effects. If you need a picture of the moving track, you can extend the exposure time, speed up the shutter speed and increase the exposure (many friends find that the subject is often blurred when shooting moving objects, mostly because the shutter speed is not fast enough. If the shutter is too slow, the result is not a track, but a blur); If you need to create a dim effect, you should speed up the shutter and reduce the exposure. Although this kind of autonomy is high, it is inconvenient and does not allow time to capture fleeting scenes.

AE mode:

AE is called automatic exposure, which means automatic exposure. Modes can be roughly divided into aperture priority AE, shutter speed priority AE, program AE, flash AE and depth priority AE. Aperture priority AE mode is an automatic exposure mode in which the photographer manually selects the aperture size when shooting, and the camera automatically selects the appropriate shutter time according to the scene brightness, CCD sensitivity and manually selected aperture, that is, the exposure mode in which the aperture is manual and the shutter time is automatic. This exposure method is mainly used for shooting occasions that need to give priority to depth of field, such as shooting landscapes, portraits or macro photography.

Multi-point measurement:

Multi-point photometry is to achieve the best photographic effect through the brightness of different positions in the scene and the compensation of flash, which is especially suitable for shooting other light objects. First, the user should measure the background of the scene, usually the light source object, and then AE lock; Step 2, measure the backlight scene. Most professional or quasi-professional cameras will automatically analyze and use flash to fill the backlight object.