Matters needing attention in flash photography

Using flash as the main elimination means of photography can create various light effects according to the photographer's creative intention. But if the flash is not used properly, the photos taken may also fail. Therefore, when using flash as the main lighting source, we should pay attention to the following issues:

Avoid messy projections.

When the flash is used as the direct illumination of the main light, it is most likely to produce eye-catching projections, and these chaotic projections will destroy the photographic picture and should be avoided.

It is true that it is obviously difficult for people who have no experience in flash photography to know the effect of flash lighting and the projection of light in advance. Due to the extremely short lighting time of the flash, it is difficult for people's eyes to clearly observe the projection position and brightness ratio in the instantaneous flash, so they can only observe its effect from the photos taken and constantly sum up their experience.

Make full use of the scene light.

In all kinds of shooting environments with flash as the main lighting elimination, except at night and without lighting conditions, there is a certain degree of lighting brightness. The brightness of these lights may be very limited for photographic exposure, but if they are combined with the light of the flash, they can form a more ideal light effect.

To choose a suitable background

The selection of background is very important when flash is used as the main lighting elimination. Generally speaking, it is advisable to choose a bright indoor place as the background, such as the doors and windows of the room, the torch mouth of the factory or the bookshelf of the library. Using these typical environments as the background to set off the main characters can achieve better results.

When shooting some people's activities that don't need to focus on the environment, especially portraits, try to choose light-colored objects as the background, such as light-colored walls and curtains, to purify the background. If you want to take a low-key portrait photo, you should choose a dark background, the backlight should use the auxiliary light of strong light, and the front light should be weak, so as to produce a low-key effect with dark background and clear characters.

In order to prevent red eye phenomenon

Taking color portrait photos with flash often makes the pupils of human eyes flash with strong red bright spots, which is the phenomenon of red eye. Usually, it is caused by flash lighting when the light is very dark, especially when the pupil of the human eye is completely open in the dark environment. In addition to considering the photographic environment, photographers are also required to have certain skills.

There are two ways to prevent red-eye phenomenon in color photography: one is to avoid taking portrait photos with flash in complete darkness during the day; The second is to avoid the front flash lighting as much as possible, so that the flash forms a certain angle with the subject's line of sight, which can avoid the direct point on the pupil.

The electronic flash with fast power supply is also an excellent auxiliary light source for outdoor photography. Whether you use an ordinary mirror or a temporary mirror, you can observe the intensity of reflected light at the shadow of an object with your eyes. Fast digital camera with reflector focusing plane are particularly useful. Because it is necessary to freeze children's play with a very high shutter speed, the flash can't keep up with the focal plane shutter camera with such a fast speed, so it is necessary to use a reflector to provide the necessary lighting.

The room is illuminated by reflective flash lamp, with soft and uniform light, natural light feeling and wide lighting range. Using an auxiliary flash with weak brightness on or near the camera can display the light of the eyes. But you have to test to determine the correct exposure time of the reflective flash in the actual shooting environment. Don't forget to record the positions of lights, cameras and subjects, the size of the lens aperture, and other important situations.

It would be better if all the above details were written down before exposure. You can draw a sketch of the shooting location, indicating the distance between points and the height of the lamp. The diffused light reflected by the flash lamp is soft to the touch. However, you may also want photos with rich details and strong texture. This performance can be achieved by using direct flash memory.

In order to make the effect better, at least two lights should be used: one is the main light, which is arranged away from the camera; The other lamp is used as an auxiliary lamp and placed on or near the camera. The triangular lighting scheme formed by these two lamps avoids the shortcomings of thick shadow and flat light caused by only one light source near the camera.

The built-in flash of the camera can be used to trigger the driving lighting installed at a certain distance. This kind of driving flash without wiring can be used as the main light source for external illumination of the camera, and the built-in flash can be used as the auxiliary light source. The same lighting arrangement can also be made for electronic flashlights with double lamp heads. Among the external light sources of the camera, the strongest light should be placed in the direction facing people.

Eliminate or weaken projection

In single-lamp flash photography, ugly shadows are often left behind the main characters, which seriously affects the aesthetic feeling of the picture and the performance of the main characters. Flash can be eliminated or weakened in the following ways:

Avoid vertical composition

In single-lamp flash photography, the flash is placed on the top of the camera. When shooting in horizontal composition, the flash light source comes from directly above the lens, and the shadow is relatively weak. When the picture is vertical, the flash projection falls on the side of the character, leaving a thick black projection consistent with the outline of the character on the background, which makes the picture very ugly. Therefore, single-lamp flash photography should avoid vertical composition.

Select background

When shooting indoors, every room has bright windows under natural light. We just need to arrange the subject in front of the window, or choose a suitable shooting angle to make the window the background of the subject, so that the flash projection will disappear on the bright window.

Shoot with a slow door

In indoor single-lamp photography, in addition to the flash light source, there are natural light and indoor lighting from the window, but the latter two kinds of light are too weak to make the subject have enough exposure. However, as long as we shoot with a long shutter time, we can make full use of indoor light to weaken the projection left by the flash. When shooting, you can lean against the wall, tables and chairs and other supports, use the slow door of115-1/4 seconds, and use a tripod if possible to prevent vibration. By the way, in indoor panoramic photography, the flash often fails to illuminate people far away in the room. If you use the usual flash to synchronize time shooting, the foreground of the picture will often be overexposed, and the consequence is underexposure. At this time, slow door shooting can also be used to effectively use lighting and indoor natural light to make the illumination of the whole picture more uniform.

Man and wall

When people are close to the wall, the space between people and the wall is relatively narrow. Indoor light and natural light can't shine or reflect on the wall, making the subject leave a strong flash projection on the wall. So, if possible, keep the subject away from the wall, and then shoot with the slow door. Flash projection will be significantly weakened.

Flash lamp with soft lampshade

Some flashlights are equipped with a soft plastic cover like frosted glass, which can soften the flash. If there is no soft leather, you can use a white handkerchief or gauze instead, and the effect is also very good. When using, handkerchief or gauze should be close to the surface of flashlight. If the soft light effect is not ideal, you can add two or even three layers. However, when a soft cover or soft fabric is added to the flashlight, the illumination of the flashlight will decrease, so the exposure should be increased. Generally, after adding a plastic soft mask, you should open a large aperture, and add a thin handkerchief to open a large aperture.

Use white walls to reflect light.

The so-called "reflection flash method" is to aim the flash lamp holder at the white reflector in the ceiling, wall and other rooms, and use the reflected light to illuminate the subject. In single-lamp flash photography, the "reflection flash method" can be used to change the lighting direction from the original front light to the front top light or front side light, so that there will be no projection on the picture. However, because this method will damage the light, it is generally about two levels larger than the original aperture value to get accurate exposure. For details, you can calculate how many levels of aperture to open as follows:

Aperture = (flash index/distance from flash to reflector+distance from reflector to object) X-ray reflectivity

In the above formula, "light reflectivity" varies with the surface texture and color of the reflector. For white walls in general rooms, the reflectivity can be substituted into the formula by 0.7, and the reflectivity of dark walls is even lower.

Six methods of reducing or eliminating projection in flash photography are introduced above. These methods should be used flexibly according to local conditions in actual shooting, so as to take more perfect flash photography photos.