How to reduce noise in digital SLR shooting and post-processing

First of all, you can try low-sensitivity shooting when shooting. After increasing the sensitivity, the inherent thermal noise of the sensor will inevitably be amplified, and the final picture will appear more noisy. Generally, for most digital SLR cameras,

You can take clearer photos at a sensitivity lower than ISO400. If you are very picky about the performance of noise, you may want to always fix the sensitivity at the lowest value provided by the camera. However, this method is not perfect. Low sensitivity will inevitably lead to the need for a slow shutter when the light is dim to ensure adequate exposure. Without the help of tripod or optical anti-shake technology, it is difficult for us to take a stable picture. In addition, some Canon digital SLR (such as EOS 1Ds Mark II) will reduce the dynamic range when using the lowest sensitivity provided by extended mode (the lowest sensitivity is ISO 100, but the extended mode provides ISO 50 sensitivity).

The second biggest cause of noise is underexposure. In the case of underexposure, pictures often show more noise, especially in the shadow area of the image. Therefore, if you are very picky about the performance of noise, you can increase the exposure compensation when shooting (adjust the exposure compensation to +0.3EV or +0.7EV), which will make the picture look brighter and reduce the impact of noise on the image quality. However, this method also has some disadvantages. After the picture is slightly overexposed, some highlights will be lost.