Technical terms for evaluating photography

Exposure: exposure is what we usually call "the brightness of a photo", that is, the amount of light entering the lens and shining on the photosensitive element will be affected by aperture, shutter and sensitivity.

In addition to the influence of the three elements of exposure, we can also adjust the exposure of photos by adjusting the exposure compensation. Common exposure situations are: normal exposure, underexposure, overexposure and accurate exposure.

Aperture: Aperture is a device to control the light input of the camera, which consists of a set of blades that can be opened and closed (the greater the opening of the blades, the smaller the middle aperture, and the less the light input). The aperture is represented by f on the camera, and the value of f is opposite to that of the aperture. The greater the f value, the smaller the aperture, the less the amount of light, and the darker the photo; The smaller the f value, the larger the aperture, the more light entering and the brighter the photo.

Shutter: Shutter is also a device to control the amount of light entering the camera. It controls the amount of light entering the camera by controlling the time when the light enters the camera (which can be understood as a device for controlling the exposure time). Shutter is measured by the speed on the camera in seconds (s); The larger the shutter value, the more light enters and the brighter the photo; The smaller the shutter value, the less light enters and the darker the photo.

ISO: Sensitivity is a numerical value used to judge the sensitivity of the camera sensor to light, which is expressed by ISO on the camera, such as ISO200 and ISO300；; ; The larger the ISO value, the brighter the photo and the rougher the picture quality. The smaller the ISO value, the darker the photo and the better the image quality. It should be noted here that the higher the sensitivity, the better. High brightness will cause rough picture quality!

Focal length: the focal length is simply how far or how wide the camera can shoot; The longer the focal length, the farther the shooting distance and the narrower the viewing angle; The shorter the focal length, the closer the shooting distance and the wider the viewing angle.

White balance: use the white balance of the camera to restore the true color of the object, and adjust the white balance by adjusting the color temperature. So we can also adjust the white balance to achieve the desired picture tone.

The white balance is K.K. < 3800 K, and the color of the photo is cold; 4000K & ltK & lt5500K, the color tone of the photo conforms to the actual environment; K & gt5500K, the color of the photo is warm.

Depth of field: Depth of field is the distance from the clear part to the blurred part in the picture, which can be understood as the degree of background blur. There are two factors that affect the depth of field: aperture and focal length. The larger the aperture: the shallower the depth of field; The smaller the aperture, the deeper the depth of field; The greater the focal length, the shallower the depth of field: the smaller the focal length, the deeper the depth of field.

Color temperature: Color temperature is the most common index of spectral quality of light source, and we often use K to express it. For example, the color temperature of natural light is around 3300K K, and the color temperature can show the cold and warm effect under different light; The higher the color temperature, the colder the photo will be; The lower the color temperature, the warmer the photo will be.

Door B: When we press the shutter button/cable release, B will appear on the camera, and the shutter will remain open all the time. You must use a tripod to shoot door B, which is often used to shoot the night scene and the starry sky at night.

AEL: automatic exposure control lock. With this function, you can point out the parts that need to be exposed correctly when shooting, such as the face, press the shutter half-way to determine the exposure and focus, and press the lock key, and the camera will lock the exposure.

EV: EV is the exposure index of the camera. Exposure is combined by different shutters and apertures, and the exposure achieved by different combinations is the same.

Quan Huafu, half frame: frame refers to the size of the photosensitive element area; Quan Huafu sensor is a camera with a length and width of about 36 mmx 24 mm. Because it is as big as the negative of traditional 135 film, it is also called 35mm frame and 135 frame. The photosensitive element size of a half-frame camera is 22.7* 15.5mm, and that of Quan Huafu is about 23 times that of a half-frame camera. So the body of a full-frame camera is bigger than that of a half-frame camera.

Focus: (AF) Auto focus: It means that the camera will start auto focus when the shutter is half pressed, and will stop focusing when the focus is locked. At this time, no matter how to move the position to compose the picture, the focus is fixed; Auto focus is the best way to shoot fixed things. Autofocus is the most time-saving and error-prone for beginners.

(MF) Manual focusing: It refers to a focusing method to achieve clear focusing by rotating the lens focusing ring. Manual focusing in the digital camera era is generally used when autofocus fails, which is a powerful supplement to autofocus. Manual focusing is more selective and effective.

Contrast: Contrast refers to the difference range between the brightest part and the darkest part of the picture, that is, the strength of the contrast between light and dark in the photo. If the difference range is large, the picture contrast is large; The difference range is small, and the picture contrast is small.

Light-dark boundary: The light-dark boundary, as the name implies, is the boundary between the dark part and the bright part in the picture. When we shoot with harsh light, the boundary between light and shade will be obvious, while when we shoot with soft light, the boundary between light and shade will not be obvious.

Out-of-focus: Out-of-focus is a bad phenomenon that the expected focal plane does not coincide with the actual imaging focal plane due to the equipment itself.

In short, defocusing means that the focus determined by the camera through the autofocus system is inconsistent with the actual focus when we shoot, and the focus is biased.

Out-of-focus: Out-of-focus is generally caused by the accuracy of the focusing system or external light, which means that after focusing is locked, the subject or camera leaves the original position, resulting in focusing deviation.

Defocusing and defocusing are actually similar. Out-of-focus is only applicable to autofocus cameras. It is the moment when the camera's computer presses the shutter after focusing that it makes a misjudgment. A small gesture drives the lens, causing the focus to drift and leave the original position.

Noise: Noise is the rough part of the image produced when the sensor outputs light as a received signal, which is usually caused by electronic interference.

Shooting mode

AUTO: The exposure parameters in auto mode are controlled by the camera, and the operation is fully automatic.

P: Program Automatic Mode (P) "Semi-automatic" mode can be adjusted except the parameters of aperture and shutter.

AV/A: Aperture priority mode (A/AV) requires manual aperture control, and other parameters will be automatically adjusted by the camera. Most subjects can be photographed.

S/TV: Shutter priority mode (S/TV) can manually control the shutter speed, and the aperture is automatically adjusted by the camera. ISO can be manual or automatic.

M: Manual mode (M) Manual control of exposure parameters (aperture, shutter, sensitivity, etc. ) it is more complicated.

Storage format of photos

There are two storage formats for photos: RAW and PEG；; RAW format: The detailed information of photos will be preserved for later retouching. But the file memory is very large, which requires a lot of storage space. JPEG format: The details of photos are saved very little, so the corresponding memory occupied by files will be small, which is easier to manage. So if you need retouching later, you can save the RAW format +JPEG format to facilitate retouching. If you don't need retouching, just save the PEG format directly.

Classification of lens

Small spittoon: Small spittoon is the nickname of Canon EF50mmF/ 1.8 lens; Its large aperture of 1.8 allows it to provide faster shutter speed for shooting in low light environment to ensure the success rate of film production. At present, it is also used to refer to a lens with a focal length of 50 mm

Biscuit head: Biscuit head refers to a kind of lens with short length (that is, very thin) in SLR lens. Because it looks like a biscuit, it got the nickname biscuit head.

In order to pursue the ultimate compact size, this kind of lens sacrifices the proportion of the maximum aperture and even the image quality of the lens. Generally, the maximum aperture of biscuit head is only F2.4-2.8.

Big ternary: Big ternary lens refers to three zoom lenses with constant F2.8 maximum aperture. These three lenses are only responsible for ultra-wide angle, standard zoom and telephoto, and together they can cover the most commonly used focal segments from ultra-wide angle to telephoto. (Canon and Sony are 16-200mm, Nikon is 14-200mm, and Pentax is15-200mm); Therefore, it is called "big ternary". At the same time, only the top-grade constant aperture lens can be named "Big Ternary".

Small ternary: Small ternary lens refers to the general name of three zoom lenses with constant F4 aperture.

These three lenses are only responsible for super wide angle, standard zoom and telephoto. Together, the two can cover the most commonly used focal length (generally 16-200mm) from super wide angle to telephoto. Therefore, it is called "small ternary". Only a constant aperture lens can be called "small ternary". Canon Small Ternary refers to three constant aperture red circle lenses with a maximum aperture of f4.

Smoothing: the light source is face to face with the object being photographed, and the light shines directly on the object being photographed.

Photometry: The irradiation direction of light forms an angle of about 90 with the shooting direction of the camera. Using sidelight shooting, the subject can have a sharp contrast between light and dark, making the picture very textured.

Backlight: refers to the light coming from the direction of the subject's back to the camera, which is called backlight and is a kind of lighting with artistic charm and strong expressive force.

Top light: refers to the light that shines on the subject from above, and keeps a vertical angle of about 90 with our camera. In nature, the most common top light is the midday sun. Usually, when shooting still life and other objects that need to show the details of the top of the subject, the top light is used.

Soft light: generally refers to indirect light. For example, on cloudy days, the contrast between soft light and dark is small, leaving no obvious shadow. Generally speaking, soft light is more suitable for shooting.

Auxiliary light: it exists as a supplement to the main light when shooting, and its function is to fill the shadow.

Flash, reflector: Common light supplement tools, whose main function is to strengthen exposure (increase the brightness of photos) when shooting.