What should I pay attention to when taking black and white photos?

Black-and-white world digital black-and-white photo shooting skills 2007-06- 14 2 1:36 because of its small tolerance, digital can't show as many gray levels as black-and-white silver salt. But the most basic, pure black, pure white and intermediate tones can still be photographed. Of course, there are not as many layers as silver salt, and the expressive force is poor. So pay more attention to exposure when shooting. My overall feeling is that the highlight should not exceed level 2 and the darkness should not be lower than level 3, so the maximum tolerance is within level 5. It means that within the range you want to shoot, if you want to show every detail of the picture, the exposure value difference between the brightest place and the darkest place should be within level 5. For example, use spot metering, shoot in aperture priority mode, and set the aperture F5.6 If the shutter speed of the brightest point on the screen is 1/500 seconds, the shutter speed of the darkest point should not be lower than 1/8 seconds, otherwise the details will not be seen in the dark. This tolerance data should be a digital SLR. For the popular DC, because the CCD is smaller, the tolerance is smaller! So why does the camera with11.8-inch CCD show better image quality than the camera with 1/2.7-inch CCD? In addition to the noise factor, the tolerance is also very different. Understand the exposure characteristics of DC, and then return to how to expose it. In fact, in the natural environment, the light ratio of most scenes (that is, the ratio of the brightest and darkest brightness) is far above level 5, so we don't always need to show all the details clearly when shooting. Therefore, it is very important to express the photographer's creative intention by determining the appropriate exposure combination. The master in this field is Adams of the United States, and his divisional exposure method is a milestone in photography technology. I'm afraid this post can't solve the partition exposure method in detail, but its principle is actually not complicated: the sensitivity of film and CCD is less than the brightness range of the natural environment. Adams divided the brightest (pure white) to the darkest (pure black) into 10 regions (later he further divided it into 1 1 regions), and usually black and white silver salt tablets can be used. Color negative film can represent 6 regions, color reversal film and DSLR CCD can represent 5 regions, and popular small numbers can represent 4~4.5 regions. Therefore, when shooting, firstly, according to the shooting intention, determine the position of the intermediate tone you want (the so-called 18% gray level, which is the calculation basis of camera metering), and then measure the brightest and darkest parts of the picture to see if their brightness exceeds the above performance range. If so, you need to find a way! For example, a portrait with backlight, if the photometric measurement of the face is taken as the standard, the background highlights will be too bright. If the highlight needs details, it is necessary to improve the brightness of the face to narrow the brightness difference of the whole picture. Usually, we can fill the light with a flash or a reflector. Let's take another opposite example: taking portraits outdoors on a cloudy day, the light is peaceful, and the characters taken have no three-dimensional sense, especially black and white photos, which are all gray. At this time, it is necessary to use a flash or an external light to improve the brightness of the character. If the light hits the face, the face is still exposed, and the background brightness will naturally be insufficient and darkened, so that the subject will be clearly highlighted. When shooting scenery, we often encounter such a scene: blue sky and white clouds plus green mountains and green waters are very beautiful to people. The photos that can be taken back are either blue sky and white clouds, the sky is dark below, or green mountains and green waters, which is also caused by the brightness of typical actual scenes exceeding the tolerance of photosensitive materials (film or CCD). The traditional solution is to add a polarizer or a medium gray gradient lens to reduce part of the brightness of the sky and narrow the brightness range. Another method, especially suitable for DC, is to take two photos, one based on sky exposure and the other based on ground exposure, and then combine the two photos in Photoshop. Note that this method is best to use a tripod to ensure that the shooting positions of the two films do not change, otherwise the later synthesis will be very troublesome. As can be seen from the above, it is very important to know the brightness information of each area on the shooting screen to get a photo with appropriate exposure, so the spot metering function is very useful. Most popular digital cameras now have metering function. Of course, the area of this "spot" looks larger than that of traditional "spot" metering, but it is usually enough. There are two points to note when using spot metering: First, any metering is based on the gray board condition with reflectivity of 18%, that is to say, an image with gray level of 18% is obtained by exposure according to the metering value, and the gray level of 18% is approximately close to the back of China's hand. Second, the exposure determined after obtaining the photometric value is centered on the middle gray tone required by the picture, and the details to be retained should be within the range of positive and negative brightness. For example: shoot a flower in the sun with a tree in the background, and shoot it against the light. First of all, determine what we want to express: first, flowers need to have quite complete details; Second, the trees in the background are expected to change obviously in hue and gray with the flowers. If the flowers are light, the background should be dark to highlight the flowers. Composition and color matching are not considered here for the time being. Okay, how do we shoot it? First of all, under direct sunlight, the part of the petal that is illuminated will have a high brightness. Compared with other dull parts, the brightness difference is often beyond the range that CCD can express, so that the film taken directly is either a piece of dead white flowers without details or a group of dark spots that can't be seen. In fact, solving this problem is very simple. It is best to prepare a piece of white gauze with sulfuric acid paper for tracing, soften the sunlight shining on the subject and reduce the light-dark ratio, so as to ensure that the light-dark part of the flower is within the exposure tolerance and can show enough details. Secondly, we don't want the background of the flower to be similar to the brightness or tone of the flower, which will make the main body less prominent. One way is to atomize the background with a telephoto lens or a macro lens with a large aperture, and the other way is to choose the background on the backlight surface, which will naturally darken the exposure based on flowers because of insufficient brightness. Of course, the darker the background, the better. Sometimes appropriate details are also helpful to express the theme. Finally, the exposure problem in black and white photography is discussed. Black-and-white photography has no color factor, and it is completely expressed by brightness change. Therefore, the composition of black, white and gray in a photo is essential. In addition to the change of hue, lines and areas with different lightness are also the core elements of picture composition. In addition, in many cases, black, white and gray are also contrasted with each other. Therefore, when shooting black and white film, it is more necessary to accurately understand the brightness composition and contrast factors on the screen, and determine the exposure combination according to the creative intention. Black-and-white photography should pay special attention to things that look very different to the human eye, but are difficult to distinguish in the black-and-white world, such as red flowers and green leaves. In the color world, the contrast is very sharp, but in black and white conditions, it is all gray, and the brightness difference is very small. So when shooting, if you want to show the difference between red flowers and green leaves, you need to use color filters. Of course, the color of DC shooting can be converted to black and white by selecting the red channel, discarding other channels, and then converting to black and white. Reference:/33/15 _ 323779.html.