How does a SLR focus at night without lighting assistance?

Method for set external flash lamp without auxiliary focusing lamp in darkness

1. Note that flash exposure compensation and flash will accumulate in the machine.

Some people are used to adding and subtracting exposure compensation directly with cameras, but forget that exposure compensation may have been used for flash. Because some cameras will automatically accumulate values, exposure compensation will accumulate, resulting in excessive exposure deviation of photos. Of course, there are also camera systems with independent exposure compensation for flash, and exposure compensation for flash on camera is not acceptable. In addition, some flashlights have exposure preference settings, which can adjust the exposure compensation when TTL flashes in advance. If the photographer forgets, he may think that the flash is not allowed.

(1) Each flash has a light button, which not only prompts the charging situation, but also triggers the test flash or modeling flash, and the output of the test flash can be adjusted.

(2) The most basic test flash output can be set to full output.

2. Is the high-speed synchronous flash bright enough?

Most digital SLR are equipped with high-speed synchronous flash function, some are called FP, some are called H or HSS. High-speed synchronization means that the camera can use a higher shutter and a compatible flash than the highest synchronization. For example, the highest speed flash synchronization shutter of a camera is about 1/200 seconds. Shutters above 1/200 can be used after installing the flash and turning on the high-speed synchronization. However, the maximum output of the flash will be weakened after FP is turned on, because the flashing time of the flash is shorter, the joint output will be reduced accordingly, and the GN value will also be reduced. Please refer to the instruction manual for the actual value. In fact, the flash will display the effective flash distance in real time, so once you use FP, you should pay attention to the shooting distance, in case of insufficient brightness. Some cameras use FP for high-speed synchronization. Others use H for high-speed synchronization. When using FP, after the shutter exceeds the highest flash synchronous shutter of the original camera, the effective flash distance of the flash will be greatly shortened, and the main body distance will be about 2 meters, which will not be bright enough when using FP.

3. The camera focus assist light will be invalid.

Why is the focus assist light not on? Some people even ask why the auxiliary lights are different every time, but they are not. It may not be turned on because this feature is turned off. This option is set on the flashing light. If you don't want these focused beams to affect the subject during shooting, you can turn them off, but it is very necessary in a dark environment. Some photographers like to use auxiliary focus, but they don't want to use flash. In fact, some flashlights also have this function option. As for the beam of auxiliary light, most of them are strip-shaped, and different numbers and positions of horizontal lines and straight lines will be emitted according to the position of focus. There is a focusing auxiliary light in front of the flash, mostly a red light beam. Advanced flash and focus assist light can emit corresponding lines according to the needs of camera focusing system for focus position, so they will be different.