Flash sync! Is my understanding correct? .

Brother, I understand what you mean, it's good, I'll add a little bit to you;

Here we first have to know two things:

1: The flash time of the flash is much faster than the shutter speed.

Take the Canon 580EX II as an example:

Flash brightness Flash time.

1 1 1 1000 seconds.

1 2 1 2000 seconds.

1 4 1 4000 seconds.

1 8 1 9000 seconds.

1 16 1 15000 seconds.

1 32 1 21000 seconds.

1 64 1 30000 seconds.

1 128 1 35000 seconds.

2: We need to know how the curtain shutter works;

The curtain shutter camera has two curtains: the front curtain and the rear curtain. The front curtain blocks the lens, and the back curtain is on top of the front curtain; After pressing the shutter at a slow shutter speed (e.g. 1 60 seconds), the front curtain begins to move downwards and light begins to enter until the front curtain is fully opened, and the rear curtain begins to move downwards to block the light.

Knowing this, bro, you'll be able to better understand flash sync.

Flash synchronization is also divided, front curtain synchronization, rear curtain synchronization;

Slow Sync is an advanced feature that the camera implements with the flash. The slow synchronization of the flash refers to the early morning, evening or night with a certain amount of lighting, appropriately reducing the shutter speed, and using the flash at the same time, which can ensure the normal nature of the subject while making the background appropriate and enriching the picture effect.

There are two modes of slow sync: pre-sync and post-sync. Forward sync, which flashes as soon as the shutter is fully open, is suitable for general situations and is convenient for capturing shooting moments, such as the demeanor of a person; Post-sync refers to the flash of light when the shutter is about to close, which is suitable for shooting moving objects, and can pull out the movement trajectory of moving objects to form a strong dynamic effect.

Nowadays, the shutter opening time of a typical camera is 30 seconds, 1 2000 seconds or 1 4000 seconds, and the top body can reach a shutter speed of up to 8000 seconds (Minolta even has a body that can reach a shutter speed of 1 12000 seconds).

Flash synchronization means that when taking pictures, the flash must be synchronized with the camera shutter, otherwise the flash will not make the sensor get the auxiliary light obtained by the flash. The flash synchronizer is designed to synchronize the external flash with the shutter in multiple forms: direct wire connection

radio connection; flash synchronizer; Wait; The camera shutter is very fast, in flash synchronization, the focal plane shutter is between 1 60 seconds and 1 250 seconds, and the inter-lens shutter may be more than 1 300 seconds, requiring the flash to fire with the shutter open, otherwise, it will not be effective, or **incomplete. Generally, the luminous time of gas flash lamps is 1 1000 seconds to 1 200 seconds. The special one can be shorter and possible to reach the microsecond range, and the flash time is short, which allows the moving object to be "stationary" on the image sensor and obtain a clear image.

Flash, one is fast, the other is time.

When the shutter is open, the flash does not emit light, then the subject is in a state of insufficient (of course, if the illumination is too low, it will not leave an image on the film), but the film can still record the insufficient image, and the subject is in motion, so what is recorded on the film is a smear.

When the time of 1 4 seconds or 1 8 is up, that is, the moment before the shutter is about to close (I don't have the exact time data), the flash glows, and then the shutter closes.

At this point, due to the flash light, the subject leaves a clear, **sufficient image on the film, and then the shutter is immediately closed, so that at the last point of this string of clips, there is a clear subject illuminated by the flash. The effect is a ** with a sense of movement and speed.

When shooting with flash, the foreground subject** is very good, but the background is less effective. This problem is minimized by the Slow Sync Flash, which takes longer to open the shutter and makes the background fully sufficient**.

In most cases, when using a slow shutter, a fast-moving subject or camera shake can cause the image to become blurry, and the way to prevent this blurring is to use a tripod or shoot a still subject. Capturing fast-moving objects with short flashes often produces interesting effects, and flash-type Edharu captures subjects that tend to be clear, while long periods of time without flashes** can create blurry images of subjects.

So how do you set up "Slow Sync Flash"? Most cameras have this function setting, you can refer to the camera instructions to operate.

1. ISO is the first sensitivity, if it is a TTL flash, then increasing the ISO in TTL mode will reduce the flash output, which also means a higher continuous shooting speed and a shorter recycle time. The cost is poor picture quality.

2. The shutter and the flash should be synchronized, otherwise the shutter is open, the flash is not on, or the flash is on, the shutter is not open, and you can't shoot**, and you will be sad. The reason why the original lamp is several times more expensive than the auxiliary lamp is because the original lamp is 100% synchronized, and the analogue's cannot.

3. Yes, it means that the control of the flash, not on, useless. If the overall control is the overall ** compensation.

4. Synchronization is needed at any time, there are front curtain synchronization and rear curtain synchronization, the front curtain is to flash first, and then open the shutter, the rear curtain is to open the shutter first, and then flash at the last moment. Synchronization is a broad meaning that means that the flash works perfectly with the camera, and generally speaking, the camera needs to be synchronized with the flash at all times.

Hope it helps.