What are the main indicators for buying a digital camera? Ask for a detailed answer.

First of all, before buying a camera, you must have a general positioning of your choice. In addition to the price and main use, there are also several times of optical zoom and how many pixels are needed (the higher the photo, the bigger it can be). A little deeper is the lens quality, CCD sensor (the larger the size, the better the imaging quality) and LCD size, wide angle (that is, field of view and shooting range), anti-shake, manual, continuous shooting, selfie, short film, red-eye function, automatic manual mode, battery and memory card properties, and so on!

Introduce Kodak Z7590. Personally, I think it's good. With 5 effective pixels, German Schneider lens, 10x optical zoom, 3x digital zoom, 2.2-inch LCD screen, sensor 1/2.5, self-timer, multiple continuous shooting, short film shooting function, using SD card and lithium battery. Support full manual (learning photography requires full manual) or full automatic (lazy) multi-mode shooting. But it doesn't have anti-shake function. ...................................................................................................................................... bought 3/last year. Kloc-0/00 (cheaper now) = complete machine +2 256mSD Kingston cards (speed 50*)+ 1 original battery (the machine also comes with 1 original factory) +uv mirror (not the worst, the market price is around 100) and connection kit+/ If the funds are limited, the Hong Kong Bank version of 7590 will cost about 2000 yuan each! Just in case, after-sales service is more troublesome ..............

Kodak V570 (dual-lens super wide angle) is recommended for a card machine of about 3000 yuan. Many card machines will have white bubbles when shooting night scenes (Samsung I5, Canon IXUS50, Sony and other machines have this problem in their own eyes, and the reason is unknown). This problem has not been mentioned in this machine forum, and the photos posted on the forum do not have this problem!

When buying a digital camera, the best advice is: take your time and don't worry. It is important not to buy at a discount, because discounted goods are often out of date or will be replaced by newer and more advanced technologies.

When you buy a digital camera, you need to pay attention to the following points:

Buying a camera is actually buying a negative. The resolution is fixed in the camera and cannot be improved on the basis of the maximum resolution of the sensor. If the details of the image are important to you, pay special attention to the maximum resolution of the camera when choosing a camera.

Digital cameras with relatively moderate prices are mostly fools, unlike SLR cameras, which can be controlled by users themselves. This means that you can only hope that the manufacturer will equip the camera with as many control devices as possible at a given price. There are not many Pns cameras, optical accessories or other accessories. Some digital cameras are very similar to 35mm SLR cameras, but they are expensive and only suitable for professional photographers.

In short, you must carefully judge what kind of images you need, and then buy the camera that best suits your needs.

Finally, digital cameras need to store photos stored in memory. In order to achieve a reasonable cost performance, digital cameras usually use a variety of ways to compress images. Compression has a great influence on image quality, and some compression systems need to remove the details and color information of the image to obtain a relatively small image size. The direct result of this is that the image taken by the sensor is weakened. However, at present, few cameras do not lose other information when compressing and storing images.

1. sensor (CCD, CMOS)

The resolution of digital camera should not be lower than 1024X768, so as to capture more image details. Digital cameras use two basic types of image sensors: CCD and CMOS.

CCD camera is expensive, and it is likely to be replaced by CMOS technology in the next few years. CMOS cameras have just come on the market. Be careful not to confuse the interpolation resolution with the actual resolution.

2. Photometric system

Exposure meter, also known as exposure meter, occupies a very important position in the camera, because it sets the shutter speed and aperture according to the shooting scene.

The best metering system is "regional metering" or "multi-regional metering". In these systems, the camera divides the captured image into several areas, and each area is measured by the camera's photometric system. Then, the obtained results are combined and a special calculation method is used to determine the best exposure. Then the aperture and shutter speed of the camera are determined according to the information provided by the metering system. At present, there are not many digital cameras equipped with multi-area metering, but this phenomenon is gradually changing.

Today, most digital cameras use central focus average metering. This photometry focuses on the central part, and then averages the photometric values of the whole picture to determine the final exposure. That is, when the camera is aimed at a dark object, the rest of the image will be overexposed, and vice versa. The only way to know the type of exposure provided by the camera is to try it. Fortunately, when using most digital cameras, you can understand the camera's metering method by browsing the images on the LCD screen.

Finally, please remember that there is no data available in the overexposed image area, and it will not be retrieved by the image editing software in the future.

camera lens

Most digital cameras are equipped with wide-angle lenses, which is equivalent to the area range of 30 to 40mm for 35mm cameras. When shooting at this focal length, the image will be distorted, especially in the vertical direction. It is for this reason that most users prefer aspherical lens. In addition, a high-quality autofocus glass lens is very important for any camera, especially in macro mode. Some people think that it is convenient for a fixed-focus lens to shoot through the focal length, but it is more limited when it is close to the subject.

Camera speed is also important. The smaller the "f" value of the lens, the brighter it will be (F2.0, F2.8). The larger the "f" value of the lens, the smaller the maximum aperture, so only a small amount of light can reach the sensor, so the shutter speed decreases. Low shutter speed means that the captured image is easily blurred, especially when shooting a moving object perpendicular to the photographer.

Finally, pay attention to whether the lens cover on the lens is easy to fall off. It is best to string a lens rope on the lens cover, so that the lens cover is not easy to lose. Don't underestimate such a small lens cover. Generally, the original products are incredibly expensive, so you'd better be careful. Believe it or not, some quite expensive cameras don't string lenses. If you buy such a camera, you should always be careful not to lose the lens cover, or you can make a hole in the lens cover and tie a rope on it yourself.

4. Image compression

Almost all cameras compress images before storing them. Most of them use lossy compression such as JPEG. No matter how compressed, colors and details must be lost. Now, in addition to professional cameras, more and more cameras begin to provide lossless compression in TIFF format. This option is very popular with users, but the picture file is relatively large, with a size of 9Mb for 2048X 1536, and most memory cards can't store several. With the increase of memory card capacity, this problem should be effectively solved. However, we still hope that manufacturers can provide lossless compression formats for smaller files like RAW. However, in the current situation, it is best to pay attention to the final file size generated by the camera at the best resolution. The image file size is less than 300K, which means that the compression ratio is relatively high, and many details are likely to be lost.

Step 5 remember

Memory is very important for digital cameras, and now it is a necessary equipment for digital cameras. The memory provided by different vendors varies greatly. The new model is equipped with a removable memory card or a built-in storage unit, or both. Some cameras have no built-in storage unit, only one memory card, and its capacity will vary according to the manufacturer and camera model. Some older models only have a fixed amount of memory and cannot be expanded. You'd better not buy such an old model Moreover, the capacity of the built-in storage unit of different models of cameras will be different, which will affect the speed of storing files and continuous shooting. Therefore, under the same conditions, it is best to choose a larger memory.

6. Digital and optical zoom

Because the lenses of most civil digital cameras cannot be replaced, many cameras have zoom function. But you have to distinguish between optical zoom and digital zoom. If it is optical zoom, it is more practical. But we should also pay attention to whether the maximum aperture of the lens will become very small when zooming to the telephoto end. If this is the case, it is impossible for you to get a higher shutter speed when shooting with a telephoto end, and it is possible that the photos you take are empty. It should be noted that digital zoom is of little use. So don't expect too much from digital zoom, it's mediocre, just a partial enlargement of the photo.

7. Optical viewfinder

Watch out! Some digital cameras do not have an optical viewfinder. To buy such a camera, you must have a spare battery at hand. Using an LCD screen as a viewfinder will quickly drain the battery. To make matters worse, most LCD screens are of little use in outdoor light. It's best to buy a camera with an appropriate optical viewfinder. Many viewfinders are too small or have no diopter adjustment, so users who wear glasses will feel extremely uncomfortable when using them, and many viewfinders can't correct parallax. So be careful and make sure you are satisfied with the camera viewfinder. For the camera with paraxial view, there must be parallax correction line and diopter adjustment button. It would be better if you could buy a TTL viewfinder.

8. LCD screen

Digital cameras are usually equipped with LCD display screen, which can preview, play back and delete the images stored in the camera. The best LCD screens are active matrices because they display the brightest images. Its disadvantage is that it consumes more power than any other type of LCD screen. Recently, the passive matrix display screen has been improved in technology, and the screen is clearer, which can be seen clearly even outdoors. But remember: LCD is a famous electric tiger, so you'd better save it.

Finally, don't make a purchase decision just because the photos displayed on the LCD screen are good. The images seen on the LCD screen are often brighter and more saturated than the actual scenery. By the way, check the position of the camera's display screen, because the display screen position of some cameras is not very good, and when you use the optical viewfinder, your nose is just facing the LCD, and it takes a lot of time to wipe off the oil stains on your nose.

9. Control design

Complex control devices are really annoying. The control device of digital camera should be easy to operate and understand, and users can operate normally without a user manual.

Moreover, the control equipment should be easy to reach, and it is best not to set common functions in the menu. If you want to move the camera under your nose to find the control keys before taking pictures, you will lose many opportunities.

10. Flash

Built-in flash is very necessary. The camera should have basic flash control, which can automatically flash in places with insufficient light or force the flash to turn off. For small portable cameras, red-eye removal function must be equipped to prevent human eyes from being photographed as rabbit eyes. If possible, try to buy a camera that flashes synchronously with the slow door. This function can accurately expose people and backgrounds when taking pictures of people with night scenes.

Pay attention to the range and area of the flash or its index. Some types of flash can not completely cover the maximum shooting angle of the lens, which makes black corners appear in the photo. There are also some flashlights whose effective distance is too small to shoot objects at a little distance. Finally, pay attention to whether the camera can be connected with an external flash. Generally, cameras with flash hot-start or external flash synchronous terminals are better.

1 1. Image processing speed

After taking a picture, the digital camera must store the image in the memory. The time of image processing varies from a few seconds to dozens of seconds. During this period, the camera can't work normally and is very sensitive to vibration, so the shorter the time, the better.

12. Support software

Digital cameras are not enough. In order to get photos, it must be connected to a computer. Check what came with the camera to see if there is a driver accessory named TWAIN. This software can download pictures from the computer, or it should have plug-ins. Most manufacturers will provide some image editing software, which can adjust images. Even if you are not familiar with image software such as PHOTOSHOP, you can use these simple software to resize, trim, adjust contrast, color or sharpen images. Check the bundled software carefully, some parallel imports don't have this.

connect

Most cameras use serial interface to connect with computers, but this connection mode is slow to transmit data, which is no longer suitable for larger and larger image files. Other manufacturers provide IrDA connection mode, using infrared to transmit data. But your computer must have this function, many laptops have it, and desktop computers are rare. Other vendors provide IEEE 1394 or USB connection, both of which have fast download speed. Among them, IEEE 1394 is mainly used for professional models, but the computer must have the interface of IEEE 1394; USB is widely used, and now there are USB slots on general computer motherboards, which is the most ideal connection mode at present. If there is no USB connection, you can also buy a USB card reader, some can only read one card, and some can be compatible with SM and CF cards. Yes, most cameras are equipped with cables. Some cameras only provide cables for PCs, and Macintosh cables are only optional. Make sure that the camera you choose can be connected to your computer correctly.

14. White balance control

This is a very useful function. White balance allows you to control the camera to judge the basis of shooting scenes. Through this control, it is possible to prevent the generation of an image that is too dark or too bright or an image with color shift due to fluorescence. Midrange and professional digital cameras usually have this function. Although most cameras are equipped with automatic white balance control, under different light sources, automatic white balance still cannot fully meet the requirements. Therefore, more advanced digital cameras provide multi-level white balance for users to choose light sources.