Use the flash has the following two points to note.
1. Close-up shots
When using flash shooting at close range, due to the relatively close distance, and the flash mounted on the camera simply can not get the proper illumination height, there is no way to get enough distance to spread light, so there will be uneven illumination. Then you can separate flash and camera, using the camera flash line, holding a flashlight to adjust it to the appropriate location, so that the light can illuminate the subject more evenly.
Because of the flash power generally larger, shot at close range, due to the instantaneous reflection on the surface of the subject, will make the light straight into the lens, produce overexposed. Then you can put a uniform piece of the gauze in front of the flash, so weakened due to scattering of light intensity, which becomes more even and soft, effectively avoid overexposure situation.
2. Special environment
In the rain or snow scene shooting, generally do not use flash, because of the rain and snow reflective screen causes dazzling light, breaking the harmony of the picture.