Knowledge of home digital camera

Digital cameras are getting closer and closer to us, and people are beginning to know more about digital cameras. I believe every user has this feeling. When buying a digital camera, faced with numerous technical terms in promotional materials, not many of them can be understood by themselves. More often, we still listen to the explanation of the sales staff, and the sales staff will say which is better! Moreover, many users are not particularly interested in photography, so it is more necessary to let everyone know some professional terms about cameras, and when buying digital cameras, let yourself become an understanding consumer and choose your favorite products!

Basic knowledge:

Effective number of pixels: The image sensor receives the incident light passing through the optical lens. The effective number of pixels refers to the number of pixels on the image sensor, which will be directly reflected in the final output data of the still image.

Interpolation is a method to increase the pixel size of an image without generating pixels. Based on the color of surrounding pixels, the color of missing pixels is calculated by mathematical formula. Some cameras use interpolation to artificially increase the resolution of images.

Sensitivity (ISO): A popular point is to measure how much light a film needs for accurate exposure. Sensitivity is generally expressed by ISO value. The higher this value, the more sensitive the film is to light, and it can be shot in different light. In order to facilitate the understanding of digital camera users, digital camera manufacturers generally convert the sensitivity of digital camera CCD (or light sensitivity) into the sensitivity of traditional film.

White balance: color is essentially an explanation of light. What looks white in normal light may not look white in dark light, and "white" under fluorescent light is also "non-white". White balance is a technology that defines "white" as "white" regardless of ambient light.

Digital zoom: through the calculation of the program on the fuselage and the cooperation of the optical system, the subject can be partially enlarged, and the effect of optical zoom can be simulated by interpolation. It works in a way similar to enlarging a part of an image in a computer, but the difference is that "digital zoom" is done directly on the CCD during shooting. To be exact, "digital zoom" is just a cropping tool, because it can cut off a part of the image-this part is invisible when using a long focal length lens, and only the selected local area is stored.

Optical zoom: For digital cameras, optical zoom does not change the size or resolution of the picture, and the number of pixels used to describe the picture remains the same. This is the fundamental difference between optical zoom and digital zoom, which is reflected in the image, that is, the image quality will be different.

Exposure compensation: it means that after the camera measures light, it can be adjusted in series to achieve an image similar to the actual light, which is exposure compensation.

Manual exposure: the combination of aperture and shutter can be controlled freely, and the shutter speed display in the viewfinder can provide adjustment of aperture or shutter to obtain correct exposure. If necessary, you can deliberately increase or decrease the exposure to create special effects.

Lens focal length: refers to the distance from the focal point to the lens after the parallel light passes through the lens. Basically, if the position of the subject remains the same, the focal length of the lens will be proportional to the magnification of the object.

Aperture: the number of aperture sizes at all levels is called the aperture coefficient, which is expressed by f/ and is the reciprocal of the relative aperture, such as1:3,5, and the aperture coefficient is f/3.5 or 3.5. The smaller the aperture, the less light enters, and the difference between numbers is 2 square roots per level, such as 1, l.4, 2, 0.

TTL: through the lens, that is, the single-lens reflective viewfinder.

AF (Auto-focus) Auto-focus: There are two ways of auto-focus, which can be divided into active and passive according to the control principle. Active autofocus is to use the camera to emit a beam of light (usually infrared), determine the distance of the object according to the reflected light signal, and then automatically adjust the lens to realize autofocus. Passive focusing is a bit bionic, that is, it is accurate to analyze whether the object is in focus, but it is difficult to focus accurately in low illumination because of its complex technology and high cost, and it is mostly used in high-end professional cameras. Some highly intelligent cameras can also lock moving objects and even control the focus with their eyes.

AE (Automatic Exposure): Automatic exposure means that the camera automatically determines the exposure according to the light conditions. From the basic principle of photometry, it can be divided into incident type and reflection type. The incident type determines the exposure combination by measuring the brightness of the light shining on the camera. Reflection method is an ideal method to determine the exposure combination by measuring the actual brightness of the subject, that is, the brightness of the image. From the perspective of metering methods, it can be divided into spot metering automatic exposure, center focusing automatic exposure, multi-point balance automatic exposure and so on. , each with its own advantages and disadvantages, is suitable for different lighting conditions or shooting purposes. From the control process, it can be divided into aperture priority, shutter priority, mixed priority, program control and predetermined mode.

Aperture priority: first determine the aperture to be used, and then the camera determines the appropriate shutter speed according to the calculated exposure. This method is suitable for situations where a predetermined depth of field is needed or the light ratio is adjusted with a flash.

Speed priority: first determine the shutter speed, and let the camera choose the appropriate aperture size, which is suitable for shooting moving objects; Mixed priority is to make up for the deficiency of single priority by first determining the range of aperture or shutter, and then determining the exposure combination by the camera.

Program control: it is to expose the camera according to the pre-programmed control program.

Predetermined mode: The manufacturer preset reasonable exposure parameters for shooting according to several common lighting conditions.

AWB: (automatic white balance) automatic color adjustment, which automatically senses and adjusts the color temperature according to the light source of the shooting place.

Color temperature: refers to the difference scale of the color of the object caused by different types of light sources.

Proprietary technology part:

ISAPS technology: (Chinese name: intelligent scene analysis based on photographic space) is a unique technology of Canon, which applies statistical analysis technology to improve the performance of AF, AE and AWB. Canon can get the settings of relevant focal length, focal length, scene brightness and other factors by analyzing the frequency and parameters of users taking pictures. Depending on the statistical frequency of different combinations in various situations and advanced prediction algorithm, Canon digital camera can optimize AF/AE/AEB in any scene more accurately, quickly and effectively. (Canon know-how)

Broadband digital technology: make full use of the space of memory card to record moving images and sounds to the maximum extent. (Olympus know-how)

Multi-point intelligent autofocus: (Multi-point AiAF) Wide-area autofocus can automatically select one or more focuses on the subject in the picture. Combined with iSAPS technology, it can achieve faster and more accurate autofocus in various shooting environments. (Canon know-how)

Flexizone AF/AE: Flexizone AF/AE AF/AE function, the photographer can move the autofocus point freely in the picture, and when the subject is not in the center of the picture, there is no need to re-compose. When users choose spot metering, they can choose the focus point in the view frame, so as to adapt to the complex lighting environment to a greater extent. (Canon know-how)

Digital ESP metering system: Choose the appropriate exposure mode in different environments (even in very bad lighting conditions). It can ensure accurate exposure results even in the case of backlight or high contrast. (Olympus know-how)

Spot metering system: measure light at 8 o'clock at most in the same picture, read a specific area in the photo, so as to obtain the desired accurate effect, and use exposure locking.

Center-weighted average photometry: based on average photometry, the images at or near the center of the image are calculated according to different weighting coefficients, with the center having the largest weight, and the closer to the edge of the image, the smaller the weight. The final value is the photometric value.

Storage medium part:

CF card: CF card was first introduced by SanDisk Company in 1994. This storage medium adopts flash memory technology and can store information permanently without power supply. Fast speed, light weight and only the size of a matchbox.

XD Card: (Ultimate Digital Card) is jointly developed and held by Olympus, Fuji and Toshiba. Olympus and Fuji saw that SM cards could not keep up with the trend and technology, so they jointly launched a slimmer and more advanced XD card.

MMC card: Multimedia card, which is a multi-functional memory card jointly developed by SANDISK Company of the United States and Siemens Company of Germany, can be used to carry digital products such as telephones, digital cameras, digital camcorders and MP3 players. It has the characteristics of small size, light weight and impact resistance, and can be read and written 300,000 times repeatedly.

SD card: Secure digital card-Secure digital memory card is a multifunctional memory card with large capacity, high performance and especially security developed by Panasonic, Toshiba and Sandisk. Compared with MMC, it has a password authentication function (SDMI specification) for data copyright protection. Now it is mostly used in MP3, digital video cameras, e-books, microcomputers, AV equipment and so on. , its reading and writing speed is 4 times faster than MMC card, reaching 2 MB/s. At the same time, it is compatible with MMC card, and most sockets of SD card support MMC card.

Sony memory stick: Sony memory stick is a digital storage medium of ultra-small volume (chewing gum size) integrated circuit jointly developed by Sony Corporation with Casio, Fujitsu, Olympus, Sanyo and Sharp in July 1997.

Image save format:

Exif format: (short for exchangeable image file-exchangeable graphic file) is a format specially set for digital camera photos. This format can record the attribute information of digital photos.

Exif2.2 is a new and improved digital camera file format, which contains all kinds of shooting information needed to achieve the best printing.

DPOF (Digital Printing Order Format) format: This is a standard printing order data format. When consumers want to print the images in digital cameras through personal cameras or printers, or send them to professional printing service centers to output photos, they will automatically transmit the recorded ordering requirements to the output devices.

DCF format: It is a unified recording format for digital cameras. It is the abbreviation of the design rules of camera file system in order to facilitate the use of portrait files between related devices in the specifications of JEIDA.

RAW format: the original recorded data on the sensor (CCD or CMOS) is directly read, which means that these data have not been processed by exposure compensation, color balance and gamma adjustment. To put it bluntly, there are no human factors and no compressed images. Therefore, professional photographers can use special software, such as Photoshop, to perform exposure compensation, color balance, gamma adjustment and other operations on photos in the later stage.

TIFF: abbreviation for label image file format. It is different from other bitmap files that can record preview images and large-capacity content information. Because its software package can ignore unreadable information, it can be said that its file format is relatively independent of the platform.

10 Suggestions for beginners of photography

First, keep the camera stable.

Friends who have just learned to shoot movies often encounter the problem of blurred pictures, which is caused by camera shake, so avoid camera shake when shooting. Generally, the left hand holds the machine, the elbow presses the chest, or the body leans against a stable object. When using a telephoto lens, be sure to add a tripod. The method of pressing the shutter should be steady and gentle, and the whole person should relax. After breathing well, hold your breath and shoot. When shooting from a low viewpoint, the camera can keep sitting or kneeling to enhance stability.

Second, let the sun be behind you.

Photography is the perfect combination of light and shadow, and it needs enough light to illuminate the subject when shooting. The easiest way is to let the sun behind you and have a certain offset. Light can illuminate the subject, brighten its colors and shadows, and slight deviation can produce some shadows to express the texture and three-dimensional sense of the object. However, it should be noted that you should generally not let your own shadow enter the picture when shooting.

Third, the choice of shooting style.

Different ways of holding the camera (vertical or horizontal) have different images. Vertical photography can emphasize the height of the subject (such as shooting a forest), and horizontal photography can emphasize the width of the subject (such as shooting a continuous mountain range). But when shooting with a pocket camera, be careful not to let your fingers block the flash.

Fourth, change the shooting style.

We should constantly try new shooting methods or emotional appeal in shooting, otherwise watching too much will give people a unchanging feeling. Personal shooting is very casual, and you can shoot anywhere. As long as you find the picture interesting or meaningful, you can play it at will. For example, you can take some close-ups of people, panoramic images, the same scene in different climates and so on.

Fifth, reduce the shooting distance.

Sometimes, you don't have to photograph the whole person or thing, but emphasize a unique place in the scene, which will have a stronger visual impact. As long as you are close to the subject, you can get better results than long-distance shooting.

Sixth, enhance the visual effect of depth of field.

Depth of field is very important for shooting. Every photographer doesn't want his photos to look flat without stereoscopic effect. Therefore, in shooting, it is necessary to add some objects to express relativity and increase the depth of field. For example, if you shoot a distant mountain, you can add a person or a tree in the foreground of the picture. Using a wide-angle lens can exaggerate the perspective relationship between the normal space and depth of the subject.

Seven, the correct composition

The easiest way to highlight the subject in photographic composition is to put the subject in the center of the picture. Because the subject is in the center of the picture, the whole picture has a special stability. But always putting the theme in the middle will be boring. A good photo usually has a very suitable composition. Golden section composition is common in photography, that is, the picture is divided into three parts (horizontal and vertical) on average, and then the subject is placed on the bisector or intersection. Therefore, it is advisable to use the golden section to make the composition diversified.

Eight, capture the details

You can shoot a big scene with a wide-angle lens, but such shooting will make you lose a lot of details, especially meaningful details. So sometimes you have to use a zoom lens to make the picture smaller and capture an interesting little picture.

Nine, focus on shooting people in advance

When shooting people, you can wait for them and adjust the exposure and focal length in advance after determining the shooting position and angle. Strive to complete the shooting in a short time, reduce the tension of the subject, and get photos with natural expressions. The weather is changeable and the light is changing, so it is necessary to take more pictures to have enough images for the final choice.

Ten, give full play to the best role of the lens.

For general cameras, the best aperture for shooting skills is 5.6-8, and the maximum aperture is set to 2-3 steps in the direction of small aperture. Keep the camera stable, master the correct grip and body posture, and choose a higher shutter speed, such as 135 camera 100 mm lens, and it is best to use1125 second speed. If you have to shoot at a slow shutter speed, use a tripod to keep the camera stable and ensure that the photo image is clear. Lens filters with different colors can produce obvious tonal differences between some colors of the scene. Ultraviolet filters can protect lenses from rain and fog, while minimizing the influence of ultraviolet rays in coastal areas and mountainous areas.

Teach you how to choose a digital camera

Teach you how to choose a digital camera

Author: Zou Zhenqing

Although there are many brands and models of digital cameras on the market at present, they all have many similarities. Most models have color viewfinder, and the color LCD screen used to preview or play images has the functions of image stability control, special effects processing (fade in and out, slide in and out, etc.). ), automatic white balance function, optical zoom more than 10 times, still image shooting function similar to digital camera, etc. However, due to the different grades and manufacturers of digital cameras, we need to pay attention to the following aspects when purchasing: single CCD or 3CCD high-end video recording and playback machine, whether it is single CCD or high-end video recording and playback machine. 3CCD model has high resolution and vivid color reproduction, but its optical structure is complex, its circuit structure is simple, its maintenance is convenient and its failure rate is low, but its price is relatively expensive. Single CCD focal length filter is just the opposite, and the actual definition is poor. However, now the single-chip CCD of home cameras can reach the resolution of about 400 lines, which is enough for home use and can be said to be cheap and good. LCD viewing and electronic viewing LCD screens have a large viewing area, which can rotate in a wide range of angles, and some can rotate 360 degrees, which is convenient for viewing. In addition, this display can also be used as an AV monitor, and it can also be turned into a small LCD color TV through a TV tuner, which is quite useful for traveling abroad. Its disadvantages are weak display under strong light, high power consumption and high price. More practical is the electronic viewfinder, which is cheaper, saves electricity and can be used in any environment. Although the viewing angle and color effect in the viewfinder are not exactly the same as the final effect, they will adapt quickly after being used for a period of time. Focusing and white balance autofocus are common functions of cameras, but this focusing method usually focuses on the center position, so there is nothing you can do when shooting a subject that is not in the center of the picture. In addition, when tracking shooting, the auto-focus function is very limited, and manual focusing is more casual at this time. White balance is an indicator of the camera's ability to truly restore the color of the scene in different occasions. At present, digital cameras are equipped with automatic white balance function. However, if there is no manual white balance function, your camera, like a camera, can only be called a "fool machine", and you can't get the best color reproduction and special color picture. For example, if you want to make the night sky look gloomy, if your camera only has automatic white balance function, the photos you take will become neither fish nor fowl. Optical zoom and digital zoom optical zoom rely on the structure of optical lens to achieve zoom. In order to make full use of the pixels of CCD as much as possible, the captured image is as clear and natural as possible. Good camera manufacturers use high-quality optical lenses. For example, Sony has equipped the latest digital cameras and digital cameras with Zeiss lenses, which are called the best optical lenses in the world. In addition, the maximum aperture of the lens can not be ignored when purchasing, because in the current home digital camera, large aperture means low illumination shooting. Digital zoom is actually a kind of picture enlargement, which enlarges a part of the original CCD image to the whole picture, and supplements an intermediate value by copying adjacent pixels, giving people the illusion that the picture is enlarged visually. In fact, the quality of the pictures taken by digital zoom function is rough and the images are blurred, so it is of little practical value. Still image storage and video output At present, digital cameras have the function of shooting still images, so it is best to choose a digital camera that can use a memory card when purchasing. Digital cameras can use I. Link digital input/output (IEEE 1394 standard) to directly input images into computers. In order to make it convenient for users to play images directly on the TV set at home, digital cameras sold in the market now basically have analog output interfaces. As long as the analog video and audio output terminals are connected to the corresponding input interfaces of the TV set, they can enjoy their own images, which is very convenient. However, it should be noted that some digital cameras do not have analog video and audio output terminals, and only through the conversion adapter can the digital signals in the cameras be converted into analog signals and input to the TV. Lithium batteries and Ni-MH batteries, which are small in size and battery size, rechargeable and have no charging memory, have been widely used, so cameras using these two batteries should be chosen when purchasing.