Photographic curtain

This problem only occurs in cameras with curtain shutter structure, and there is generally no mirror shutter in professional cameras.

For structural reasons, adjusting the shutter speed is actually adjusting the shutter opening. This shutter sweeps across the film plane in the form of different aperture sizes. The faster the speed, the narrower the aperture.

It must be understood that adjusting the shutter speed does not mean adjusting the moving speed of the curtain. The moving speed of the curtain is fixed, generally about 2 meters per second.

For this reason, only at a certain shutter speed (slower than this speed) can the gap be fully opened, and only when it is fully opened can the film be completely illuminated by the instantaneous flash. When it exceeds this speed, some light will be blocked by Hou Lian and become out of sync.

How to avoid it? You're definitely not a photographer. It doesn't matter whether the shutter speed is 30 or 200. For outdoor shooting, you can only use a flash that is lower than the synchronous speed. Another solution is to use flash lamps that can synchronize at high speed, such as original lamps or U2 speed lamps (not listed). As for why the high-speed synchronous lights don't shadow, that's another question.