How to use stage lighting with LED large screen

The development of large LED screens has brought great convenience and a broader creative space to today’s stage designers, and has become a stage with full expressiveness and eye-catching stage design elements, making the points, lines, and surfaces on the stage all It has become an important part of the show of stage art, combined with augmented reality technology, creates an artistic atmosphere that is also true and illusory for stage lighting.

However, any new technology is a double-edged sword. It is very important to use large LED screens reasonably and reasonably; otherwise, it will inevitably bring many problems and troubles, and even go to the opposite side. Therefore, how to deal with the relationship between the stage lighting and the large LED screen, make the two cooperate and complement each other, and provide a more beautiful picture for the audience, it is the practitioners should think and explore in depth.

Change the lighting design concept

Before the large-scale appearance of self-luminous elements such as large LED screens, the brightness and darkness of the scene on the stage and the overall light effect of the picture were controlled by lighting designers. When a large number of self-luminous elements enter the camera's composition, the design concept of TV lighting has gradually shifted from lighting design for dark environments to the balance of light effects for bright scenes, that is, balancing the illuminance and color temperature of the light source of the lamp and the large screen, and balancing the main character Brightness and color with glowing background.

In the production of traditional TV lighting, it reflects the contrast relationship of object brightness. The camera restores the brightness of the object being photographed. When the illumination and contrast meet the requirements, the level, tone, and clarity of the picture can achieve satisfactory results. After the large LED screen is used as the main background in the TV variety show, the lighting engineer must take its self-luminous characteristics into account when designing it, and treat it as a large LED lamp. Because of the difference in video content display, its brightness , Colors also have different changes. Under the premise of not affecting the stage effect and ensuring the basic illuminance, the lighting layout should be adjusted continuously. Not only must the brightness and light ratio of the lighting be reasonably used, the level contrast of the actors and the scenery must be controlled. The actor and the LED large screen balance the brightness and master the overall color change of the stage; make the color temperature tone and content of the party lighting harmonious and unified, so that the large LED screen is fully integrated into the TV stage and integrated with the TV lighting, so that the TV picture can be real Natural color reproduction.

Adjust light ratio, aperture, color temperature, video

The application of large LED screens has an impact on the basic illumination of the stage, the level of character modeling and color reproduction. After the large LED screen is used in a TV variety show, its own luminous brightness affects the effect of TV recording to a certain extent: when the illumination in the performance area is constant, if the brightness of the large screen is too high, the face of the actor will be dark; the brightness of the large screen If it is too low, the audience will not be able to see the content clearly. Lighting design needs to balance the brightness of the main character and the illuminated large screen. Because the presentation of the TV screen and the clarity of the image do not depend on how bright the entire screen is and the use of a large amount of lighting, the key lies in the use of appropriate light and dark contrast and corresponding light properties. The light illuminance of a good TV picture is not necessarily very high, but lies in the proportion of light used appropriately. We all have this experience: when recording TV programs, the director often feels that the picture is "not bright enough" and asks to increase the illuminance of the light, but often the brightness is increased, and the brightness of the large screen behind the background is also higher, in the middle and close shots The large screen will be brighter than the human face, causing the human face to be dim. The level of the character picture is not prominent, and the quality of the picture cannot be improved.

Some practical methods

(1) Dimming ratio

The light ratio between the face and the background can be reduced by increasing the brightness of the characters in the stage performance area or reducing the brightness of the large screen. If the brightness of the characters in the stage performance area is increased, on the one hand, it will inevitably increase the number of lamps and the capacity of the power supply equipment, which will cause a series of problems such as heat dissipation; and in general, if the illuminance of the performance area can reach 1000

lx, it can already meet the shooting needs of high-definition cameras. Therefore, most of us adopt methods to reduce the brightness of large screens. The distance between the camera and the large screen is about 15 m～18m, and the LED large screen self-check color bar is the standard. According to the size of the large LED screen, the brightness should be adjusted to about 25% for larger than 20 m2, and about 35% for less than 10m2. . However, if the actor is close to the large LED screen and it takes a long time to shoot, as the content and color of the large LED screen change, the face of the person in the close-up picture taken by the camera will be dark, and the background will show a whitish mosaic situation; at this time, You can locally increase the lighting of the character's face, and then adjust the aperture to balance the brightness of the character and the background of the foil.

(2) Fixed aperture

Due to the continuous improvement of camera sensitivity, and many programs have been shot in high-definition, the studio will use lower illuminance when recording programs, usually controlled at 800 lx-1000

Around lx, the aperture is between F4 and F5.6. It is generally believed that F5.6 is the better aperture value. The general experience is: during the actual recording rehearsal, the lighting engineer and the video technician will first determine a basic aperture range according to the program form, and this range must always be guaranteed to be in the best working condition of the camera, that is, between F4 and F5.6. In this aperture range, complete the basic lighting arrangement required by the camera, determine the brightness of the large LED screen, and then do the artistic embellishment of computer lights and effect lights. In this way, the video technicians of each program can adjust the aperture in a small range on this basis to ensure the visual effect of the picture and the technical quality requirements.

(3) Balance color temperature

The camera is more sensitive to the color temperature of the light source. If the color temperature of the light source is lower than that required by the camera, the shot picture will be reddish; otherwise, the picture will be bluish. Variety shows often use a variety of stage lamps. In order to ensure the color effect of the TV recorded in the party, the color temperature of the various lamps should be kept as consistent as possible. Nowadays, it is popular to use a large number of computer lights for surface lighting, that is, to use high color temperature lamps. Because the large LED screen is a high color temperature device, if the computer light uses a low color temperature lamp of about 2800K～3200K, and the exposure is based on the human face, the large LED screen shot will appear blue, causing color distortion; such as surface light adjustment It is a high color temperature lamp, which is consistent with the large screen at the back, so that the image can be presented uniformly.

(4) The materials displayed on the large LED screen can be adjusted appropriately

Because of the use of large-scale LED screens, the brightness produced will directly affect the stage lighting. At the beginning of the lighting design, we can first consider the large LED screen as a part of the stage lighting. Measure the average brightness of all broadcast materials, edit and adjust the video screen brightness and color of the broadcast materials in advance, and adjust the brightness appropriately according to the background materials and lighting design requirements of the actual program without affecting the overall large-screen effect. , And calculate the amount of light into the basic illuminance of the light, and consider the large-screen playback material content as a part of the lighting design, which can also greatly reduce the impact of the large-screen on the light and camera aperture control.