What are the technical terms in photography?

If you want to learn photography, you should buy a book. It's all in books. Some terms will naturally be understood when you use them, but not necessarily when you define them. Focal length: the distance from the center of the lens to the clear image formed on the film plane (other photosensitive materials). The focal length is usually in millimeters (mm) and is usually marked in front of the lens. For example, we usually use 27-30mm, 50mm (also known as "standard lens", which means 35mm film), 70mm and so on (telephoto lens). Aperture: A device that controls the amount of light passing through a lens. If you open the first aperture, the amount of light entering the camera will double, and if you narrow the first aperture, the amount of light will be reduced by half. The aperture size is expressed by f value, and the order is as follows: F/ 1, F/ 1.4, F/2, F/2.8, F/4, F/5.6, F/8, f/1,f. Extended reading: application of aperture shutter: device for controlling exposure time. Generally, it can be divided into mirror shutter and focal plane shutter. Shutter speed: the time when the shutter is open. It refers to the time (exposure time) when light sweeps across the film (CCD). For example, "1/30" means that the exposure time is 1/30 seconds. The shutter speed of1/60s is twice that of1/30s. The rest and so on. Depth of field: the relatively clear range of an image. Depth of field depends on three factors: focal length, camera distance and aperture size. The relationship between them is: (1) The longer the focal length, the shorter the depth of field; The shorter the focal length, the longer the depth of field; (2) The longer the shooting distance, the longer the depth of field; (3) The larger the aperture, the smaller the depth of field. Extended reading: What is depth of field preview? In order to see the actual depth of field, some cameras provide a depth preview button. Press the button to reduce the aperture to the selected size. The scene you see is the same as that recorded on the film (memory card) after shooting. Sensitivity (ISO): Indicates the photosensitive speed of photosensitive materials. Units are expressed in degrees or fixed. For example, "ISO 100/2 1" means a film with a fixed sensitivity of 100 degrees /2 1. The higher the sensitivity, the more sensitive the film is (that is, the less light is needed to shoot the same photo normally in the same shooting environment, that is, a higher shutter or a smaller aperture can be used). Color temperature: Different pigments contained in different kinds of light are called "color temperature". The unit is "k". The color temperature we usually use is 5400 K-5600 K; The color temperatures that light types A and B can adapt to are 3400K and 3200K respectively. Therefore, different types of films should be selected according to the subject and environment, otherwise there will be color cast (unless the color temperature is corrected by color filter). White balance: Due to the different spectral characteristics under different lighting conditions, the photos taken often have color deviation, such as blue under fluorescent light and yellow under incandescent light. In order to eliminate or reduce this color shift, digital cameras can adjust color settings according to different lighting conditions, so that the color of photos is as undistorted as possible. Because this adjustment is often based on white, it is called white balance. Exposure: The process in which light reaches the surface of the film and makes the film sensitive. It should be noted that by exposure, we mean film exposure, which is a necessary process for us to obtain photos. Often depends on the combination of aperture and shutter, so there is the word exposure combination. For example, the shutter measured by the exposure meter is 1/30 seconds, and the aperture should be 5.6, so F5.6 and 1/30 seconds are an exposure combination. Exposure compensation: used to adjust underexposure or overexposure. "Stop": There is no corresponding Chinese word on the Internet, and the English full name is exposure unit. It is only a unit to measure brightness, but only if there is a reference object. You can't say that an object is three stations brighter, but you can say that object A is three stations brighter than object B, but turning it into an exposed unit is not entirely in line with its original intention. It is the unit of brightness change. But only if there is a reference. This method is used because there is no standard boundary to define light and shade. A black stone will look brighter in a bright place than a gray stone in the dark. Blur: The picture is not clear. It may be caused by out-of-focus and camera shake. Pixel: In short, it is the number of photoelectric sensors on CCD/CMOS. The photosensitive element forms a point on the output photo after photosensitive, photoelectric signal conversion, A/D conversion and other steps. If you enlarge the image several times, you will find that these continuous tones are actually composed of many small squares with similar colors, which are the smallest unit "pixels" that make up the image. Pixels are divided into CCD pixels and effective pixels. Most digital cameras on the market now label CCD pixels instead of effective pixels. Resolution (ppi/dpi): refers to the number of pixels expressed or captured in a unit length. Like pixels, there are many kinds of resolutions. The most common is the image resolution. We usually say that the maximum resolution of digital camera output photos refers to the image resolution, and the unit is ppi (pixels per inch). Red eye: When a digital camera shoots a portrait in flash mode, the pupil of the human eye will appear red spots in the photo. In a dark environment, the pupil of the human eye will be enlarged, and at this time, the strong flash will be reflected on the lens through the fundus of the person. There are abundant capillaries in the fundus, and these blood vessels are red, so erythema is formed. Red-eye prevention is a function of the flash, which is to flash once before the official flash to narrow the pupil of the human eye, thus reducing the phenomenon of red eye. CCD: Translated as "Charge Coupled Device", just like the negative of a traditional camera. The more CCD pixels, the larger the size of a single pixel, and the clearer the collected image. Therefore, although the number of CCD is not the only key to determine the image quality, we can still regard it as one of the important standards of camera grade. CMOS: "Complementary Metal Oxide Semiconductor". The function is equivalent to CCD. AE lock: abbreviation for automatic exposure control device. AE lock is locked on a certain AE setting, which is used to manually control the exposure during automatic exposure to ensure the normal exposure of the subject. There are several points to note when using AE lock: AE lock cannot be used in manual mode or self-timer. Do not adjust the aperture size after pressing AE lock. Don't use (AE) lock when shooting with flash. SM flash card: smart media, smart media card, a storage medium. SM card adopts ss FDG/ flash memory card, which has the characteristics of ultra-small, ultra-thin and ultra-light. Its volume is 37 (length) ×45 (width) × 0.76 (thickness) mm, and its weight is1.8g. It has low power consumption and is easy to upgrade. SM conversion card also has PCMCIA interface, which is convenient for users to transmit data. Optical zoom: when shooting at a distance, the object is magnified, because it depends on the focal length of the lens, so imaging does not affect the picture definition. Contrary to digital zoom. Digital zoom: It can only reduce the size of the original image and make the image larger on the LCD screen, but it does not help to make the details clearer. SLR camera: The photographer can directly observe the image passing through the lens from the viewfinder. After the light reaches the reflector through the lens, it is refracted to the focusing screen above to form an image. Through the eyepiece and pentaprism, we can see the scenery outside in the observation window. This structure is completely shot through the lens focus, so that the image seen in the observation window is always the same as the image on the film. Noise: "particles" in digital images are usually caused by high ISO setting, long exposure or excessive brightness enhancement of images that are seriously underexposed on computers. Mega: the prefix of "million" in English, for example, megapixels (MP). Saturation: indicates the brightness of the color. Lens flare: the messy light is gathered on the screen to form a blurred image, which is called flare. Further reading: What is glare? It means that when strong light is projected on the film (photoreceptor) during exposure shooting, it is reflected to the surface of the film base through the emulsion of the film, resulting in blurred image. Quote/article/category/photography