What camera is the best and takes the clearest photos?

Compared with traditional cameras, traditional cameras use "film" as the carrier for recording information, and the "film" of digital cameras is its imaging device, which is integrated with the camera and is the heart of digital cameras.

Digital cameras use photosensitive elements as imaging devices to convert optical information in images into digital signals. At present, there are two kinds of photosensitive elements:

One is the widely used CCD (Charge Coupled Device); The other is a new CMOS (complementary metal oxide semiconductor) device. The resolution of a digital camera refers to the number of photosensitive elements in the camera.

CCD (Charge Coupled Device): CCD is a solid-state electronic photosensitive imaging element composed of a large number of tiny photodiodes and decoding and addressing circuits. There are two arrangements of photodiodes. One is a planar array in which a plurality of photodiodes are arranged on a plane, and optical signals (color, intensity, etc.). ) are simultaneously sensed. The working principle is similar to traditional film. This method has fast photosensitive speed, but high cost. The other is a strip array, which arranges a plurality of photodiodes in a straight line, performs photosensitive imaging line by line, and transmits optical signals line by line to the storage medium of a digital camera. The working principle is similar to that of a scanner. This method has the advantages of long exposure time, simple process and high imaging quality.

CMOS (Complementary Metal Oxide Semiconductor): In recent ten years, CCD devices have always occupied unparalleled advantages in the photosensitive elements of digital cameras. With the development of research and manufacturing technology, CMOS devices stand out with the advantages of random reading ability, excellent functional integration (easy to integrate with A/D analog-to-digital conversion circuit and DSP digital signal processing circuit, low manufacturing cost), low power consumption and working voltage. At present, the application of CMOS devices in primary products of digital cameras has basically met the requirements, but the application in high-end products needs to be improved. The main problems are that the anti-interference performance is worse than that of CCD devices, and the quality and effect of digital images (resolution, color reproduction, etc. ) are not as good as CCD devices.

2. Pixels of digital cameras

Because it is often necessary to output a large format, a digital camera with a large pixel value is naturally the first choice. This is also the most important index to measure a digital camera. It should be reminded that the pixels here are the actual pixels of CCD in digital camera, not the pixels of output image. At present, 4-5 megapixel digital cameras have fully entered the domestic market, and they will undoubtedly replace 3 megapixel digital cameras and become the new favorite of enthusiasts. At present, a 4 megapixel digital camera can easily output beautiful 8-inch photos and good quality 15-inch photos. A 5 megapixel digital camera can output beautiful 18 inch photos, even photos in A3 format (slightly smaller than 18 inch). In addition to the number of pixels, there are many indicators to understand. The area of CCD is also an important indicator that is easily overlooked. From the production process of CCD alone, the smaller the area, the higher the integration, the better. From a photographic point of view, the general public digital camera uses a 1/3 inch CCD. Such a small imaging area requires high-quality images, which requires specially designed high-density imaging lenses. Therefore, for the CCD with the same pixel, generally choose a larger area, which is more sure to obtain high-density and high-definition imaging.

Step 3: lens

Regardless of digital factors, the lens is the first factor in choosing a camera. Many photographers have been worried that the lens of digital cameras is less than a penny, and they think it is impossible to obtain high-quality images. In fact, that is a misunderstanding, because the photosensitive element of digital cameras is CCD, and the CCD used in popular digital cameras is generally 2/3, 1/2, 1/3 inches, and its area is much smaller than the traditional 35mm film, so the lens pair is the size of a coin. 6), of course, this is unimaginable for a traditional camera with a 35mm lens. But then again, the larger the camera lens diameter, the better, because a large lens is conducive to the clarity of the imaging edge. A high-quality lens with a large aperture, multiple lenses and aspherical lenses is definitely the first choice for semi-professional photography. Another important index of the lens is the focal length. Many friends who are new to digital cameras may be shocked: what! 9mm lens says it's a small wide angle? In the traditional concept, the 9mm lens does not say that fisheye glasses are also super wide-angle. In fact, the reason is the same as above, because the CCD area is small and the nominal focal length value is also small. Another important factor is the zoom range. Generally, a zoom of 2x or 3x is used. It is recommended to buy a product with a 3x zoom, because Volkswagen cameras are generally 35mm lenses, and the 3x zoom is just above 100mm, which is more practical.

4. Manual control function V

Whether there is a manual control function is the standard to distinguish a fool camera from a professional camera. Manual control here means that you can manually adjust the aperture, shutter and focal length of the camera, which is very important for semi-professional photography. Unfortunately, at present, only a few popular digital cameras have this function. Ekfa ePhoto 1280 really has manual control function, because it can manually set the aperture and shutter value at the same time. There is also Kodak DS DC 120, which can manually control one of the shutter and aperture, but not at the same time, because they are mutually restricted. So digital cameras without manual control can't be used in semi-professional fields? It's not that bad, otherwise there would be no choice. Some high-end popular digital cameras have the functions of some professional cameras, such as fixed-point metering and focus locking, which make up for the shortage of manual control to varying degrees.

5. Framework approach

Today's digital camera * * * has three viewing modes:

Ordinary optical framing: This is the most common framing method, and its only disadvantage is that the framing error is large, especially when shooting up, down, left and right positions at close range, the error between the seen image and the actual image is large, and the image seen by the viewfinder is only 85% of the actual image.

LCD framing: this is almost necessary for digital cameras at present. The advantage of LCD framing is that it corrects the shortcomings of ordinary optical framing. However, LCD framing also has some defects: first, LCD is a big power consumer, accounting for more than 1/3 of the total camera power consumption; 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't get stable triangular support, so it is difficult to take stable and clear photos with a low-speed shutter, which is really a taboo for professional photography. 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, so it is impossible to observe the specific details of shooting. Fortunately, digital cameras are equipped with ordinary optical viewfinder and LCD viewfinder almost at the same time. In the semi-professional field, you must think twice about buying a digital camera with only an LCD viewfinder, unless you fix it on a tripod all day.

TTL (through lens) SLR viewfinder: This is a necessary viewfinder for professional cameras, and it is also an optical viewfinder that really has no error and passes through the lens. Unfortunately, among the popular digital cameras, only the two most advanced models of Olympus have never been seen by other brands. The viewfinder can reach 95% of the real shot. The only drawback is that if the lens is too small, the viewfinder will darken, which will affect the manual focusing. Fortunately, now everyone has autofocus, which is no longer a big problem. Of course, if TTL SLR viewfinder is used, in order not to make the viewfinder too dark, manufacturers will use large-caliber advanced lenses, so the lens diameter on two advanced models of Olympus is 43mm, which is really the "big brother" in popular digital cameras.

6. White balance control

The concept of white balance does not exist in ordinary cameras, because the film sensitivity has been fixed, only when CCD is used as a photosensitive element. Generally, it is automatic control, but as a semi-professional use, it is best to have a white balance manual control function, which can shoot many unexpected effects.

7. Some characteristics related to professional photography

Fixed-point metering function: The fixed-point metering function is particularly important when the aperture and shutter cannot be controlled manually. Automatic exposure is generally obtained by TTL weighted average photometry, and fixed-point photometry can measure the main scene first, and then expose according to this photometric value.

Exposure compensation: This is a function that only advanced cameras have. By adding exposure compensation to fixed-point photometry, the defect that exposure cannot be controlled manually can be made up.

Focus lock: This function is very effective when the subject is out of focus. Through this function, you can measure the subject first, then lock the focus and re-compose the picture.

ISO equivalent value of sensitivity: Digital cameras use ISO equivalent value to measure the dynamic range, which is equivalent to the photosensitive speed of ordinary film and has a direct impact on contrast and granularity. The lower the ISO value, the higher the resolution, the wider the tone range and the lower the image contrast.

Shooting delay: there is a time delay between pressing the shutter and actually shooting the image of the digital camera. The shorter the time, the better, preferably less than 0.5 seconds. If it exceeds 1 sec, the practicality of this camera will be greatly reduced.

Color depth: Color depth is an important index to measure the color resolution of digital cameras. The higher the photoelectric conversion accuracy of photosensitive elements in digital cameras, the higher the color depth. The color depth of each color on a digital camera is 8 bits, and the color of each pixel is a mixture of red, green and blue. Therefore, the number of colors that a 24-bit true color image can contain is 256×256×256, that is, 654.38+67 million.

Shooting interval: After a photo is taken by a digital camera, there is a process of compression and storage. It is impossible to shoot continuously at this time. The length of this interval is related to shooting mode, compression mode and shooting scene. Generally speaking, this time should not exceed 10 second.

About the report on February 2, 2008