The ISO sensitivity is an international unified indicator for measuring the film photosensitive speed standard using film photosensitivity, which reflects the speed of film sensitivity (in fact, silver elements and optical reaction velocity of the light). Conventional cameras can choose low speed, medium or high-speed film of different ISO sensitivity according to the specific conditions of the shooting site.
For digital cameras, it does not use film, but through the sensor CCD or CMOS and the associated electronic line sensing to incident light. In order to uniformly measure the uniform unit of the film used by the conventional camera, the concept of ISO sensitivity is introduced. Similarly, the ISO sensitivity of the digital camera also reflects the speed of its photosensitive.
The value of the ISO is 1 fold, and the speed of the photosensor is also improved by one-fold. For example, the sensitivity of ISO 200 is 1 fold higher than ISO100 sensitivity, while 1SO 400 has a degree of sensitivity by 1 to ISO 200, and is 4 times higher than ISO 100, and it is pushed.
When the ISO sensitivity represents the same EV exposure value, select a higher ISO sensitivity, which can obtain the same exposure amount in the case of the aperture constant. Conversely, the correct exposure can be kept using a smaller aperture without changing the shutter. Therefore, shooting in the case of light relatively dimming, often selects a higher ISO sensitivity. Of course, for SLR cameras, you can also choose the lens using a larger diameter to improve the luminous flux. For general digital cameras, because of the fixed lens, it is only possible to adapt the ISO sensitivity to accommodation in the case of dark light, especially if auxiliary light cannot be used.
The film used by conventional cameras is the purpose of improving the sensitivity of the film by different production processes. Because there is no relevant information, it is estimated that the digital camera achieves the purpose of improving the sensitivity by increasing the amplification gain. Since electronic thermal motion of electronic devices inevitably causes ingredients, the greater the gain, the larger the noise, and there will be more noise and variegasted images. In order to overcome this problem, some digital cameras use noise reduction function to minimize its impact. However, it is only possible to achieve better results within a certain range.
I have used the energy D7 and Canon G1 because there is no noise reduction function, and the image taken by ISO sensitivity to 200 is already unbearable. Even if the ISO sensitivity increases ISO sensitivity to 800, it is better than "clean" in the former. Many noise and variegism can still be seen in the case of ISO1000 and long exposure. Therefore, the noise reduction function can only be used within a certain range.
Therefore, the application of the auxiliary light (flash and reflector) should be considered when the auxiliary light cannot be considered when the auxiliary light cannot be considered when the auxiliary light cannot be considered, and finally the ISO sensitivity is improved.
For places such as frequent shooting stations, it is not allowed to use a flash or less than a single-tripod, you can try to select a large lens caliber and a digital camera with noise reduction processing. The SLR digital camera can choose to use a larger smaller lens. Come to shoot.
Night scene shooting often uses a smaller aperture and longer exposure time, if the choice of higher ISO sensitivity will inevitably generate noise and color. At this time, you can use a tripod, it is possible to use the shutter line, select a lower ISO sensitivity to avoid noise and color generation.
Various digital cameras in different ISO sensitivity is different, and should be tested, even if it is improved, it should be controlled within the scope of it. Because despite the software to be adjusted by software, it is necessary to reduce the sharpness of the image accordingly.
Therefore, when purchasing a digital camera, it is necessary to consider the choice of a camera with noise reduction function and a large lens passage, which is conducive to the shooting of weak light. Use the flash and tripods as much as possible when shooting, try not to use higher ISO sensitivity.
