A problem of overexposure of product photography flash!

When shooting a flash, the flash time is very short, usually only a few tenths of a second.

Therefore, the shutter time during flash shooting is invalid.

But for SLR with curtain shutter, there is a flash synchronization speed. Below this speed, the curtain door opens completely. Higher speed is to reduce local exposure time by reducing curtain gap. At this time, with the flash, the picture will be half bright and half dark. So when the SLR flashes, the shutter speed must be lower than the flash synchronization speed.

Each flash has a flash index, which is equal to the aperture number multiplied by the distance between the flash and the subject when shooting with a single lamp.

For example, a flash with an index of 20, when the flash is 2.5 meters away from the subject, the camera should shoot with an aperture of 8.0. The aperture of 5.6 will be overexposed and the aperture of 1 1 will be underexposed. If the distance is 5 meters, the aperture needs to be increased to 4.0.

You are shooting with multiple lights, and generally you can't use intelligent flash control.

To solve the problem of overexposure of flash, the solution is simple: reduce the aperture (increase the aperture index value) or widen the distance between flash and the subject.