Electronic digital storage format

Audio-visual format with extension. AVI can be said to be one of the earliest popular specifications. Because AVI format is not compressed, AVI video files often need 5 ~ 8 MB storage space in just a few tens of seconds. In addition, because there is no complete set of specifications for manufacturers using AVI format to refer to, there are at least more than 100 specifications derived by a single company. Although the popular audio and video playback software, such as WINDVD, POWERDVD, and even AcdSee 3R- 1, all claim to be able to play up to 60% ~ 70% of AVI files. However, from the current situation, Microsoft's Mediea Player 8.0 is the most AVI-compatible audio and video playback software. At present, it is the most common dynamic image format.

2.MOV file format

MOV is one of the most commonly used animation formats for most digital camera manufacturers. The main reason lies in its streamlined compression technology, which provides users with a good choice of audio and video at low resolution. In addition, the playing software QuickTime is authorized by Apple computer for free, which naturally increases its popularity. At present, versions above QuickTime 4. 12 can not only handle video, animation, graphics, text and sound, but even 360-degree virtual reality (VR) is not a problem.

3.Motion JPEG-AVI file format

The standard AVI format mentioned above is not compressed at all, but it is a great waste of resources in the case of limited storage space. So in 1995, a research group suggested that JPEG standard can also be used as animation like GIF. Because JPEG adopts full-color image standard, DCT, a unique distortion compression technology, removes the less important parts of image data and effectively reduces the file size. Combining animation playback ability with JPEG is called MJPEG, which is the abbreviation of Motion JPEG. Its storage extension still uses AVI to match the compatibility of dialing and playing software. Because of its simple specifications and small memory capacity, many digital cameras that do not support synchronous radio reception, such as Nikon CoolPix 9XX series and some simple webcams used for video conferencing, like to adopt this format.

4.MPG- file format

With the increasing popularity of VCD, the technology of MPEG- 1 has also been popularized. Although, at present, only a few digital cameras can support this specification of animation recording (mostly Sony in Japan). The comprehensive result of professional CCD, lens and animation technology is almost not inferior to DV. The full name of MPEG is moving picture expert group, which belongs to ISO/IEC standards (International Organization for Standards and International Electronic Technology Association). The standard of MPEG- 1 appears in 1992, which is designed to support the first generation of optical discs. The transmission speed is 1.5-4-0 Mbps (megabits per second, equivalent to about 29.97 fps) and the resolution is 352x240. MPEG has three methods to compress frames, namely intra-frame, predicted frame and bidirectional frame, to improve compression efficiency. MPEG- 1 technology can fast forward, rewind and even select time points for long-time electronic images by decoding playback programs. Files recorded by MPG can also be directly recorded on VCD and watched by VCD player.

5.ASF- file format

The introduction of MPEG- 1 has brought at least two revolutions to the computer world. One is to make electronic animation files recorded for a long time have search function, and the other is to completely suppress MP3 music. Because the record companies have been troubled by MP3 for a long time, they must make a stricter sound format that is not easy to copy to replace MP3 when formulating a new generation of audio-visual technology. For this reason, Microsoft, as a leader in the software industry, is fully promoting the popularization of ASF format: ASF format is characterized by the latest MPEG4-4 compression method for the image part and its own WMA format for the sound part (WMA emphasizes that its compression ratio is twice that of MP3, and its sound quality is similar to that of MP3, and files with WMA confidentiality clauses and design rights are not as easy to copy as MP3. )。

In addition, in order to avoid copyright disputes of WMA sound effects, a DIVX audio and video format with MP3 format has appeared in the industry. How to maintain the compressed image of DIVX with MPEG4

Stains on the camera lens will seriously reduce the image quality, appear spots or weaken the image contrast. Fingers touching the lens is inevitable, and dust and gravel will also fall on the optical devices.

This is why it is necessary to clean the camera. Cleaning tools are simple: lens paper or fine tools with fiber cloth, lens brush, cleaning suit. Never use cardboard, paper towels or napkins to clean the lens. These products all contain scratched wood pulp, which will seriously damage the fragile coating on the camera lens.

When cleaning paper is not used, put the microfiber cleaning cloth into the original container to keep it clean. Microfiber cloth is very washable and can be washed with clothes regularly. Try not to use cotton T-shirts or other fibers, because coarse gravel may seep in. If you use a brush to clean the dust and debris on the lens, do not touch the hair on the brush with your hands or fingers. The oil on your skin will infect your hair and then stick to the lens.

Another way to clean the dust on the lens is to use the lens frequently. If your camera has a lens cover, you can fix it on the camera body with a belt, a rubber band or a "lens fixing" device.

Hot and cold weather can also affect the camera. If the camera was originally placed in an air-conditioned room and then immediately placed in a hot and humid environment, fog spots would appear on the lens and viewfinder. At this time, it is necessary to clean it with a suitable paper towel or cloth. If you bring the camera into the room from the cold and dry outdoor, you'd better put it in your bag to preheat it, and then take it out and put it in the house. And carefully hold the camera to see if it is "sweating". If you sweat, take immediate action.

Professional photographer's suggestion: take a plastic zipper lock bag with you. In very humid or dusty climate, you can dig a small hole just enough to put the camera lens on the side, and then put the camera in a bag to prevent fog, moisture and dust from entering the camera, which can prolong its service life.

Finally, don't put the camera in the back seat of a car with high humidity. The car is like a stove, which will deform the plastic and damage the wires.

Many manufacturers will suggest that if you don't use the camera for more than two weeks, you'd better take it out, because the battery will leak and rot, sometimes affecting the circuit connection, making the camera unable to work normally.

(professional Chinese-English comparison table)

Related nouns

Automatic exposure locking

AE is the abbreviation of automatic exposure control device. AE lock is locked in 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: 1, and manual mode or AE lock cannot be used when taking selfies. 2. Do not adjust the aperture size after pressing AE lock. 3. When shooting with a flash, do not use (AE) lock.

Charge coupled device

Charge-coupled devices, like the negatives of traditional cameras, are circuit devices that sense light. You can think of it as tiny sensing particles scattered behind an optical lens. When light and images are projected onto the CCD surface through the lens, the CCD will generate current and convert the sensed content into digital data for storage. 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, it can still be used as one of the important standards of camera grade.

Complementary metal oxide semiconductor

Complex-educational metal-oxicle-semiconductor, Chinese translation: complementary metal oxide semiconductor.

DPOF

DPOF refers to digital printing sequence instruction, which is used to record information on storage media (image memory card, etc.). ). In this format, you can set the number of images to be printed.

EXIF

EXIF (exchangeable image file format for digital cameras) is a specification formulated by jeita (Electronic Information Technology Industry Association) to determine the way to record additional information on jpeg images and sounds.

EXIF 2.2

EXIF version 2.2 is a newly revised digital camera file format, which contains all kinds of shooting information needed to achieve the best printing.

PTP

PTP is the abbreviation of "Picture Transfer Protocol" in English.

PTP is the standard first negotiated by Kodak and Microsoft. Image devices that meet this standard can be better shared by systems and applications after accessing Windows XP system, especially in network transmission. The system can directly access these devices, upload pictures when creating online photo albums, and transmit pictures when chatting online. Of course, this is mainly for the convenience of ordinary users with little computer knowledge, and it is easier to combine cameras, application software and websites to complete some stupid functions.

GT lens

GT lens refers to the unique design of Minolta's multi-piece and multi-group lens combination. The lens is made of high-grade low-dispersion optical glass, including several die-casting aspheric lenses and so on. In other words, Minolta's G-series high-end professional traditional camera (silver salt camera) uses AF lens. Minolta applies the technology of producing G-series lens to the design and production of digital cameras, and the product produced is called GT lens.

Zeiss lens

Zeiss. Zeiss is a German enterprise, which is committed to applied research, development, manufacture and sales of high-quality products such as optics, glass technology, precision technology and electronic products. Starting from 1846, Carl Zeiss set up a workshop to produce microscopes. Zeiss lens, professional camera, photographic lens

wide-angle lens

That is, wide angle, also known as short lens. Because the focal length of the wide-angle lens is very short, the scene projected on the basement membrane becomes smaller and the shooting angle of the lens becomes wider. Wide-angle images can not only shoot more scenes, but also shoot in narrow environments.

Pixel number

The number of pixels in a digital camera includes effective pixels and maximum pixels. Different from the largest pixel, the effective pixel refers to the pixel value that really participates in photosensitive imaging, while the value of the highest pixel is the real pixel of photosensitive device. This data usually includes the non-imaging part of the photosensitive device, and the effective pixel is the value converted under the zoom ratio of the lens. For the digital camera pixel of mobile phone, it is only in the primary development stage, and the pixel number is not very high, mostly between 65438+ million-1.3 million pixels. The larger the number of pixels in a digital camera, the greater the resolution of a still image, and the space occupied by a corresponding picture will also increase.

intelligent electro selective pattern

IESP intelligent electronic selection mode. IESP autofocus means that a digital camera is divided into several blocks within the focus range (some data say that the division method is sector division), and then the focus position measured by the divided blocks is comprehensively calculated, and the best focus position is determined according to the different states of the subject. IESP autofocus often appears in the introduction of Olympus digital cameras.

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Another focus of the lens is zoom capability, including optical zoom and digital zoom. Although both of them are helpful to enlarge distant objects in telephoto shooting, only optical zoom can support adding more pixels after the main body of the image is imaged, making the main body not only larger but also relatively clearer. Usually, the larger the zoom factor, the more suitable for telephoto shooting. Optical zoom, like traditional camera design, depends on the focal length of the lens, so the resolution and image quality will not change. Digital zoom can only reduce the size of the original image and make the image larger on the LCD screen, but it does not help to clarify the details. Therefore, when buying a digital camera, you are often advised to pay attention to the multiple of optical zoom. At present, mid-range cameras generally have about 3 times optical zoom, but there are also products with long zoom function, such as 10 times optical zoom models.

optical zoom

Zooming is realized by optical lens structure. The zoom mode is similar to that of a 35mm camera, that is, the scene to be shot is enlarged and reduced by the lens movement of the camera. The larger the optical zoom factor, the farther the scene can be shot. At present, the optical zoom magnification of digital cameras is mostly between 2 and 5 times, and the optical zoom effect of some code cameras reaches 10 times. The optical zoom factor of home camcorder is 10 ~22 times, and it can clearly shoot things 70 meters away. Using a magnifying glass can increase the optical zoom factor of the camera.

digital zoom

That is, digital zoom is actually an electronic amplification of the picture. Some pixels on the original CCD image sensor are enlarged by interpolation, and the pixels on the CCD image sensor are enlarged to the whole picture by interpolation algorithm. Through digital zoom, the shot scene will be enlarged, but its definition will be reduced to some extent, which is a bit like the zoom function in VCD or DVD, so the practical significance of digital zoom is not great. At present, the digital zoom of digital cameras is generally about 6 times, and the digital zoom of cameras is about 44 times to 600 times. In actual use, 40 times is enough. If the zoom factor is not enough, you can add a magnifying glass in front of the lens. If the shooting angle is small, you can increase the wide-angle lens accordingly.

Intelligent zoom

New and unique Sony smart zoom function. It can enlarge and reduce, without enlarging particles, so that the enlarged image can maintain the original detail quality. Intelligent zoom provides different degrees of enhanced zoom function according to the choice of different image sizes. Unlike digital zoom, intelligent zoom can maintain the same image quality as the original image.

Program automatic exposure

Programmable automatic exposure is the product of the combination of electronic technology and artificial intelligence. When exposed in this way, the camera can not only calculate the appropriate exposure according to the light conditions, but also automatically select the appropriate exposure combination.

hyperfocal distance

Because the back depth of field of the lens is relatively large, people call the distance that can be clearly imaged after focusing as hyperfocal distance. Fool cameras generally use hyperfocal distance, which makes use of the feature that the scene can be clearly imaged at a certain distance with a short-focus lens, omitting the focusing function. Therefore, generally, low-grade fool cameras can't focus automatically, so they can only use hyperfocal distance. As mentioned earlier, "clarity" is not an absolute concept, and the scenery in hyperfocal distance is not really clearly imaged. Because there is no focus, it must be blurred, but the degree of blur is generally acceptable. This is the reason why the negative film taken by a fool's camera can't be enlarged too much.

LCD frame

This is the necessary way for most digital cameras to find a view at present. The only advantage of LCD framing is that it corrects the only disadvantage of ordinary optical framing. However, just like windows 98, the bug of windows95 was fixed and more bugs were generated. Let's take a look at the shortcomings of LCD framing: first of all, LCD is a big power consumer, accounting for more than 1/3 of the whole camera; Secondly, the position of LCD framing must be that both hands stretch forward and keep a certain distance from the eyes. At this time, the camera can not get stable triangular support, so it is difficult to take stable and clear photos with low-speed shutter. Finally, the color and contrast of the picture displayed on the LCD are very different from those actually seen in the computer. Even the LCD with a nominal million pixels looks rough and cannot observe the details of the main body. Faced with this kind of picture, it is difficult for you to judge whether the photos you have taken meet your requirements. Fortunately, the digital camera is equipped with both ordinary optical framing and LCD framing. If you buy a digital camera with only an LCD viewfinder, there is a certain risk unless you are sure enough to get the desired effect. (Note: Now many mainstream consumer digital cameras have completely taken pictures with LCD. )

Liquid crystal viewfinder

That is, liquid crystal display. There are black and white and color, and color has true color and false color. Pseudo color is cheap, but the effect is poor. The LCD used for framing and playback in digital cameras is almost the best TFT true color at present. There are two types of TFT LCD: reflective and transmissive. Reflective light reflects ambient light to the front, which is very different from different angles, and the display is dark, but it saves electricity and has low cost. The transmission type works by the light behind it, with small angle change and bright display, but it consumes a lot of power.

Organic Light Emitting Diode (abbreviation for organic light emitting diode)

In order to illustrate the structure of organic light-emitting diodes, a simple analogy can be made: each organic light-emitting diode unit is like a hamburger, and the luminescent material is a vegetable sandwiched in the middle. The display unit of each organic light emitting diode can generate three different colors of light under control. Like LCD, organic light emitting diodes can also be divided into active and passive types. In passive mode, cells selected by row and column addresses are lit. In active mode, there is a thin film transistor (TFT) behind the organic light-emitting diode unit, and the light-emitting unit is lit by the TFT. Active organic light-emitting diodes save electricity, but passive organic light-emitting diodes have better display performance.

Compared with LCD, OLED has many advantages. Organic light-emitting diodes can emit light by themselves, while liquid crystal displays can't. Therefore, organic light-emitting diodes are much brighter than LCD, with large contrast and good color effect. The viewing angle of organic light-emitting diodes is not limited, and it can generally reach 160 degrees, so it will not be distorted when viewed from the side. Liquid crystal needs background illumination, while organic light-emitting diode only needs the lighted unit to be electrified, so the voltage is lower and it is more energy-saving. The weight of organic light emitting diodes is much lighter than that of liquid crystal displays. Organic light-emitting diodes require less materials, and the manufacturing process is simple, and the mass production cost is 20% less than that of LCD. However, the main disadvantage of organic light-emitting diodes is that their lifetime is shorter than that of LCD, which can only reach 5000 hours at present, while LCD can reach 10000 hours. (Note: Organic light-emitting diode technology was only used in some mobile phones earlier, but it was not used in digital cameras because of pixel and life problems, and eventually it was not popularized. )

TTL SLR frame

This is a necessary way to find scenery on a professional camera, and it is also a truly error-free optical way to find scenery. The viewfinder can reach 95% of the real shot. The only drawback is that if the lens is too small, the viewfinder will be very dark, which will affect the manual focusing. Fortunately, everyone has autofocus now, and this shortcoming is no longer a big problem. Of course, in order not to be too dark, manufacturers will use large-caliber advanced lenses, so semi-professional cameras are generally equipped with such lenses. Olympus cameras often use this viewfinder.

electronic viewfinder

Electronic viewfinder (EVF), the field of view ratio of electronic viewfinder is much larger than that of optical viewfinder. For example, the EVF of Sony DSC-f707 has a field of view ratio of 99%. Electronic viewfinder is also more practical, not only cheaper, but also more energy-saving when used, and can be used in any ambient light. 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.

optical viewfinder

The components commonly used in traditional mass cameras to view through a set of lenses that have nothing to do with the shooting lens (often linked with the zoom lens on high-end stupid machines) have low cost, but they have parallax, and what they see is not entirely taken by themselves.

Universal optical frame

This is the most common framing method, and the only disadvantage is the large framing error. Friends who have used digital cameras must know that when the optical viewfinder of digital cameras is shooting at close range, there are great errors between the up, down, left and right positions and the actual shooting scene (it is not particularly obvious when it is far away). Generally speaking, the scene seen by the optical viewfinder accounts for about 85% of the actual shooting scene.

Multiple measurement mode

It is equipped with three metering modes: fixed-point metering, central offset metering and multiple metering modes to meet different shooting conditions and uses. Multi-metering mode divides the image into 49 areas, and metering each area, so that the photographed image can get a balanced exposure.

Closed exposure

Surrounding is an advanced function of the camera. Closed exposure means that when you press the shutter, the camera does not shoot at once, but shoots multiple photos in succession with different exposure combinations, thus ensuring that one photo always meets the photographer's exposure intention. To use bracketing exposure, you need to set it to bracketing exposure mode first, and shoot as usual when shooting. Closed exposure is generally used for static or slow-moving subjects, because it is difficult to capture the best shooting opportunity of moving objects because of continuous shooting of multiple shots.

Pre-flash exposure

Special pre-flash exposure function can measure the flash intensity and exposure value more accurately by using the image data received during pre-flash during general shooting or macro shooting, so that the shot image can get better exposure.

Red-eye prevention function

It refers to the phenomenon that the photographer's eyes appear red spots because of the reflection of the blood vessels in the fundus of the subject when shooting a portrait with a flash. But now most mainstream digital cameras have red-eye prevention function, but if they are not turned on, they still won't work.

Handshake function

There are two functions of digital camera to prevent hand shock: one is optical and the other is digital. Optical hand shock prevention is the same as traditional camera. The lens designed by the special envoy is arranged in the imaging optical path, which can sense the vibration of the camera and automatically adjust the optical path according to the characteristics and degree of vibration to make the imaging stable.

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Interpolation, sometimes called "reset sample", is a method to increase the pixel size of an image without generating pixels. According to 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.

Super had image sensor

Built-in ccd image sensor with "Super Hole Accumulator Diode (had)" electronic image quality improvement technology can improve the sensing performance of ccd, strengthen the digital signal processing function, effectively reduce the noise and unnecessary interference when shooting images, make the picture clearer and brighter, and have more distinct color levels, which is especially effective when there is insufficient light source or shooting night scenes.

TTL photometry

That is TTL photometry. Measuring the luminous flux through the lens has nothing to do with the parameters such as filter exposure and aperture focal length. Measurement methods are divided into average measurement, local measurement and centralized measurement. Any method of photometry is similar, but the contrast between light and shade of the subject is very different, such as backlight, or there will be different differences, such as photomicrography.

ISO photosensitive value

ISO sensitivity is a measure of the sensitivity of traditional camera negatives to light, which is usually expressed by ISO number. The larger the number, the stronger the optical rotation. Commonly used methods are ISO 100, 400, 1000, etc. Generally speaking, the higher the sensitivity, the coarser the particles of the negative film, and the worse the magnification effect. Digital cameras also use this ISO value to indicate the exposure used by the metering system.