How to use the flash

Lead: Flash is only the need of flashlight for users who take photos with mobile phones, but it can determine the success or failure of photos for photographers. Let's see how to play flash!

As can be seen from the above picture, manual point focusing+spot metering was used when shooting. First, we measure the light in the background, and we can get the correct exposure value1/20s. This number means that 1/20 seconds can make the background have normal exposure without flashing lights. On the other hand, if the shutter is lower than 1/20, the background will be too dark, and due to the limited power of the flash and the scenery in front, no matter how hard the flash is hit, it can only brighten the main body, but not the background brightness at the same time (the foreground will be overexposed while illuminating the back).

Above: 1/20s f2.8 ISO 100

It can be seen that the flash of 1/20 seconds can create the reflective texture of the doll itself, and at the same time take into account the brightness of the background to avoid taking photos with bright subject and dark background. What about a high-speed shutter?

Above: 1/250s f2.8 ISO 100

It can be seen that although the main body of the doll itself is still similar to the previous 1/20s, the background is much darker. This is because the flash can illuminate the main body, but it is not enough to illuminate the background at this power. So unless you have two flashlights to handle the brightness of the background, you can only solve the problem that the background is too dark by extending the exposure time in the case of a single flash. As for whether this will cause the subject to be blurred? Unless your subject is moving at a high speed, under 1/20s, you can't shoot a slight shake.

However, it must be noted that if the slow door is used to get the exposure of the background, at this time, even the light on the scene will often be caught in, losing the effect of flash calendering (the light on the scene will be covered by the flash). Therefore, if you want to cover up all kinds of strange colors of light (such as colorful neon lights on the stage), you must use more than two flashing lights to supplement the main body and background light at the same time to suppress the living light.

Above: 1/8s f2.8 ISO 100

Precautions for flashing lights: What determines the overall brightness? Aperture? 、? Lightning? Or? ISO？ The adjustment of exposure time is only related to the background brightness.

If you feel that the overall brightness of the flash is insufficient (or excessive), what value should you use to adjust it? In fact, the earliest flash only had the option of full power, so the brightness level of the whole photo can only rely on aperture and ISO.

Above: 1/8s f8 ISO 100

As can be seen from the above figure, under the same exposure conditions, as long as the aperture is reduced, the exposure of the whole photo can be reduced. However, at this time, some people will inevitably have questions: when should the aperture be adjusted and when should the ISO be adjusted to change the brightness?

Let's compare the above two pictures again. Did you find that the depth of field of f2.8 in the above picture is shallow? Adjusting the aperture under the lens with the same focal length is the only means to control the depth of field, so if you have to give priority to the depth of field when taking pictures (for example, large photos or macro shots must have a deeper depth of field), then you can only adjust the aperture to your desired value first, and then rely on ISO to adjust the overall brightness.

Scientists can directly adjust the output of the flash to control the brightness. For example, in the Metz flash shown above, the EV value of the flash can be adjusted in steps of 1/2 (depending on the EV adjustment in TTL mode), and the maximum value can be adjusted to EV +3. If you have tried to adjust the ISO and aperture size and still can't get the ideal exposure, then directly adjust the EV to control the flash output! However, sometimes the TTL mode of the flash is easy to shoot wrong because of too much numerical control of the fuselage, so if you are not in a hurry, you can try the full manual M mode of the flash!

Precautions in the use of flash: the angle of flash is the key to determine the imaging light and shadow effect.

I believe everyone is familiar with the word flashing light. This word means to direct the flashing light at your subject and illuminate your subject directly without any diffusion or reflection. Generally speaking, the flash of the camera itself or the flash of the mobile phone is in this form. Although it can really illuminate the subject, the effect is often dull and ugly:

The picture above is the result of flashing lights. As you can see, because the light shines directly on the doll, not only the color becomes very dead white and not bright, but also the direct light compresses the overall three-dimensional sense.

So what is jumping flash? Flash jumping is to shoot the light of the flash in another direction first, and then reflect the flash back by reflection.

The jumping flash in the above picture uses the ceiling to reflect and diffuse the flash to the maximum extent to avoid excessive concentration of light on the subject. However, the jumping flash can be used not only against the ceiling, but also against the wall to create a light atmosphere in different directions, and a large reflector can be used to control the light direction of the jumping flash. In the studio, you can often see umbrellas (actually called reflective umbrellas) inserted on flashing lights. They all use light reflection to diffuse the flickering light and avoid direct light, which is a more efficient way of light diffusion than shadowless cover.

Jumping flash is one of the most natural lighting methods, especially the jumping flash in the ceiling direction can directly simulate the atmosphere of the scene light, and both the light angle and the surface texture of the object can be closer to the real state seen by human eyes. As for the color temperature, it is not a problem as long as you shoot RAW files, so for beginners, I generally suggest that you just jump on the ceiling and flash, so as to ensure the quality of photos.

If your flash supports off-board flash, you can use flash from different angles to create different scene effects. For example, in the picture above, the flashlight shines on the doll from an inclined position through vertical reflection and flashing. The flash on the top of the camera is used to give instructions to the flash next to it, and it does not participate in the exposure itself, which is a convenient function of Nikon camera. )

In this way, you can produce the special photo effect of oblique shadow or unilateral light as shown above! However, the above picture is just a gesture. In fact, you can add a reflector and a shadowless cover to improve the texture of the light and shadow effect.