Talking about Digital Imaging (3) Digital Cameras

Introduction Digital cameras have appeared in the mass consumer market for about six years. From the beginning, only Apple, Sony, Kodak, and other brands (excluding professional digital cameras) have been believed to have surpassed 100 brands. (The author does not have official statistics.) Some brands are entirely unknown to the author. Almost all phase-mechanism companies have introduced digital cameras, and even famous manufacturers such as Hasselblad and Rollei have introduced digital cameras. Not only do camera manufacturers produce digital cameras, even computer companies such as IBM and HP have also participated in them.
I often visit video and computer products stores. I remember a digital camera appeared in a large video and electronics chain in the United Kingdom in the following year. In the following years, more and more digital camera products gradually appeared; but in the last two years, digital cameras The product is particularly large. In addition to Japan, Europe and the United States, digital cameras from Taiwanese brands such as Mustek have recently appeared. Figure 1: The LCD display is a digital camera feature that can be used as a finder during shooting, in addition to displaying photos. Digital Camera Vs Traditional Camera The biggest difference between digital cameras and conventional cameras is that the former uses an electronic photosensitive crystal (usually a color filter CCD) to record images digitally, while the latter uses an exposure film to record images. The quality of digital cameras at the beginning of development is much worse than it is now. The color is not beautiful, the resolution is low (only 150,000 pixels or less), the function is small, and the price is more than five times that of a traditional camera. The society will improve. Now the quality and price of digital cameras have been greatly improved, and they have many functions. Some good features are not available in traditional cameras. For example, they can be photographed on the back of the camera after they are photographed. Photos, instantly know if the shot is perfect. The following table compares the differences between the two: In general, it can be said that the quality of the photos taken by a traditional camera is higher than that of a digital camera. However, under certain circumstances, such as a darker environment, digital cameras can adjust the speed of light to obtain a clear photo, which is better than traditional cameras. The structure and principle of the digital camera The digital camera and the traditional camera are very similar in appearance, but the former can be smaller in size. As for the structure, the two are also very similar. Behind the digital camera lens is not a film, but a square electronic photosensitive crystal, only half an inch to an inch long, containing hundreds of thousands to millions of small crystals, each small crystal represents One or one pixel, depending on the scanning technology. The basic structure of a digital camera is as follows:
Lens - The lens of a typical civilian digital camera is not detachable from the body, but most of the external lenses can increase the Zoom effect.
Aperture - Like traditional cameras, the purpose is to control the amount of light entering and the depth of field. The aperture size represents the luminosity, represented by the f-number (for example, f 2.8). The smaller the number, the larger the aperture, and the larger the number, the opposite.
Photo: Although the general digital camera is a built-in fixed lens, can not be separated from the fuselage, but generally can also plug the lens. Shutter - Like a traditional camera, it is a shutter that controls the exposure time. If the exposure is too long, the color of the photo will become white or light; if the exposure is insufficient, the photo will be dark.
Optical Zoom - equal to the traditional camera mechanical Zoom mode, lens lens movement will zoom in or zoom out, this mechanical Zoom lens design costs higher than the fixed lens. This feature is not available in every digital camera.
Digital Zoom - Uses software operations to zoom in on the subject, but unlike Optical Zoom, it maintains the detail of the scene. This feature is not unique to every digital camera.
CCD photo-sensing crystals —The vast majority of digital cameras (including professional cameras) use CCDs as a tool for capturing images, with the same purpose of using traditional film cameras to capture images. A CCD photoreceptor crystal is just an area of ​​an ordinary card, containing hundreds of thousands to millions of small crystals, and the small number of small crystals represents the resolution. In the next issue, explain the electronic photoreceptor in detail.
LCD Viewfinder - Almost all, if not all, consumer digital cameras have a 1.8" or 2" LCD viewfinder (an LCD was introduced last time), mostly on the back of the aircraft. It represents the outside of the scope of view, it can also replay the photographs taken and review the quality.
Flashing lights - Almost all digital cameras have a built-in flash, which is also very powerful and can make up for the lack of ambient light. There are several flash mode options, such as forced flash or no flash, providing great flexibility.
Storage Media - Photos are digitally stored in memory. Popular storage media include Compact Flash, SmartMedia, and Memory Stick. The initial design was built-in memory (RAM), and the camera had no room to add more memory. But nowadays the popular design is an active memory that can increase memory at any time and provide great flexibility. Figure 4: Micro-storage media, Compact Flash on the left, SmartMedia in the middle, and Memory Stick on the right. In addition to digital cameras, there are other electronic products (such as e-hand accounts) that use it. Figure 5: Memory Stick is produced by Sony, and of course it is used in Sony digital products. Figure 6: Using the CF adapter, the laptop can also use the PCMCIA interface to read the data on the Compact Flash cartridge. Video output - Split NTSC and PAL video output, some models support both modes at the same time, and even output the sound to the TV. Not all digital cameras have this feature (see Figure 1).
Data Transfer - Digital cameras upload or download image data to a computer via a serial or com line. The newer method is to use a USB cable. Its advantage is that the speed is much faster than the former, and it is plug and play. In addition to connecting televisions and computers, some can be connected to the printer for direct output. Figure 7: Most products will come with software and wiring for users to download photos to their computers. How to buy a digital camera The decision to choose a digital camera is very personal. Depending on the purpose and needs of the user, the author can only provide precautions for the general purchase of digital cameras (the first few are particularly important):
- Resolution - The higher the resolution, the smaller the number of digital photos and the finer and clearer the picture; on the contrary, the larger the particles, the easier it is to detect a pixel.
- Lens - It is better to have an optical zoom lens that can zoom in or out of the scene. The close-up function can also be considered. The quality of the lenses is very important, and the quality of the famous manufacturers is better, such as Zeiss, Ekang and Olympus.
- Memory - is a fixed or mobile memory, the latter can convert new memory, providing greater flexibility.
- Flashing light - As a general consumer, the built-in flashing light is required. Whether the camera can be flashed at the same time depends on individual needs. It is also worth considering that the camera can have multiple flash modes.
- Video output - The need for living, entertainment or work, is also a function worth considering. - Photospeed - whether the camera offers a variety of speed adjustment, because the high speed can still operate under low light and still get a clear effect. Such as sensing range of ISO 100 to 400 or higher is a good feature.
- White Balance - Normally has automatic white balance and self-set white balance (sunny, cloudy, indoor white light tube, muffle light settings, etc.).
- Exposure compensation - There are usually multiple exposure modes, such as aperture priority, fast priority, and so on.
- Red Eye Reduction - This function is generally available.
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