The intensity of light (both solar andartificial lighting) can be very different, and visually we are not able to determine the degree of illumination, since the human eye is endowed with the ability to adapt to different lighting. Meanwhile, the intensity of lighting is extremely important in a wide variety of activities. For example, you can take the process of film or video, and, for example, growing indoor plants.
The human eye perceives light waveslength from 380 nm (violet) to 780 nm (red). Best of all, we perceive waves with a length, not just the most suitable for plants. Bright and pleasant lighting to our eye may not be suitable for plants in the greenhouse, which may not receive important for photosynthesis waves.
The intensity of light is measured in lux.Bright sunny noon in our central strip, it reaches about 100 000 lux, by the evening it drops to 25 000 lux. In a dense shadow its value is tenths of these values. In rooms, the intensity of sunlight is much less, since the light is weakened by trees and window panes. The brightest illumination (at the southern window in the summer just behind the panes) at the best is 3-5 thousand lux, in the middle of the room (2-3 meters from the window) - only 500 lux. This is the minimum illumination necessary for the survival of plants. For normal growth even unpretentious shade-tolerant plants require at least 800 lux.
We do not determine the intensity of light by eyewe can. To do this, there is a device, whose name - luxmeter. At its purchase it is necessary to specify the range of waves measured by it, tk. the capabilities of the device, although wider than the capabilities of the human eye, are still limited.
Интенсивность света также можно измерить с using a camera or a photo-intensifier. However, it is necessary to make recalculation of the received units in suites. To carry out the measurement, you must put a white sheet of paper in the place of measurement and point the camera at it, the sensitivity of which is set to 100 and the aperture to 4. After determining the shutter speed, its denominator should be multiplied by 10, the resulting value will roughly correspond to that in the suites. For example, if the exposure is 1/60 sec. lighting is about 600 lux.
If you are fond of breeding flowers and carefor them, then, of course, you know that the energy of light is vital for plants for normal photosynthesis. Light affects the growth rate, direction, development of the flower, the size and shape of its leaves. With decreasing light intensity, all the vital life processes in plants are proportionally slowed down. The amount depends on how far the light source is removed, from the horizon facing the window, from the degree of shading by street trees, from the presence of curtains or blinds. The lighter the room, the more active the growth of plants and the more they need water, heat and fertilizers. If plants grow in the shade, then they require less care.
When shooting a movie or a television programillumination is very important. High-quality photography is possible with an illumination of the order of 1000 lux, achieved in a television studio with the help of special lamps. But acceptable image quality can be obtained with less lighting.
The intensity of lighting in the studio before and duringThe shooting process is measured using exposure meters or high-quality color monitors that connect to the camcorder. Before you start shooting, it's best to walk around with an exposure meter throughout the set to identify darkened or excessively lit areas of it to avoid negative phenomena when viewing footage. In addition, the correct adjustment of lighting can achieve additional expressiveness of the filmed scene and the desired director effects.
