Advanced photography course advanced exposure technology

Lead: Want to know how to get the best exposure? Let's take a look at the advanced exposure technology in the advanced photography course, and I'll tell you.

Equipment: Nikon F90PROF camera 20mm super wide-angle lens 8 1B warm filter, tripod.

Film: fujifilm ISO50 exposure: 1s, f/22.

At first glance, this seems to be a very subtle lighting condition, but in fact it is very simple and does not need other special exposure equipment at all. This sunset photo was taken in the Scottish swamp of Rannoch. The photographer directly measured the light through TTL, and then took this photo without any exposure adjustment. This is because the photographer knows very well that his camera can correctly expose the sky and water, and record other scenes in the form of silhouette. In this way, the photographer created this very atmospheric photo.

The realization of most of the techniques and methods discussed here depends on whether readers can have a clear understanding of exposure, whether these techniques can be used in practice, and whether readers have the ability to correctly expose under various lighting conditions.

Today's cameras, especially SLR digital cameras, are equipped with complex metering devices. This makes metering and accurate exposure much easier than before. Even the integrated metering system on the most basic camera has high sensitivity and can give accurate exposure readings most of the time.

When you shoot with a digital camera, you can immediately see the photo effect and histogram through the LCD, and even display the distribution curve of a certain channel separately. So it's easy to know whether the exposure meets your expectations and correct it in time. In addition, if you shoot with RAW documents, even if there are one or two levels of overexposure or underexposure in the shooting, you can still take acceptable photos in the end. This is because any exposure error can be corrected later by software.

Although the metering system on the camera greatly reduces the possibility of exposure errors when shooting, it is not omnipotent. Occasionally, you will find that in your shooting environment, you can't rely on modern technology to solve the problem of accurate metering and exposure, but only rely on your own knowledge and experience to ensure the success of shooting. This is especially important when shooting with color slides, because even half-level overexposure or underexposure will lead to shooting failure.

If you don't know which scenes in the shooting environment will lead to the camera metering system, naturally you won't take corresponding control measures. Similarly, if you don't have a basic understanding of how the camera's metering system works, you will inevitably make mistakes in exposure. This doesn't seem very important. After all, if 95% of the photos taken can be exposed correctly, why should we care about the 5% photos that can't be exposed correctly? However, you should know that the 5% photos are often the most exciting and unforgettable. Therefore, unless you master the skills of accurate exposure under these conditions, you will miss many godsend opportunities and shoot excellent works.

Equipment: Nikon f 90 prof. Camera, 50 mm standard lens.

Film: fujifilm ISO50 exposure: 1/60s, f/ 1 1.

This photo was taken in Pamkale, Turkey, because its shooting environment is full of bright colors, which is a typical environment that can cause the camera's metering system to give underexposure results. In order to make the photo have pure white instead of dark gray, the photographer sets the camera to aperture priority mode to get the total reading, and then increases two levels of exposure through the exposure compensation device.

Equipment required for high-order exposure

Camera: Most SLR digital cameras now offer a variety of options in metering and exposure, which can make you make as few mistakes as possible in shooting. What are the most commonly used photometry? Mode？ The working principle of the machine is briefly described.

Central key metering: This is the most commonly used metering system. It measures the light intensity of the whole frame, but pays more attention to the exposure intensity of the 60% area around the center of the image. This is based on a simple assumption that the content within 60% of the image center is the most important. In general, this metering mode is reliable and can give quite accurate exposure. However, if there are a lot of bright and dark areas in the shooting scene, only by adjusting the exposure of the camera can we avoid shooting mistakes.

Area exposure: This system is very common in today's SLR, and it can provide more accurate exposure under subtle lighting conditions. Although different camera manufacturers have different definitions and explanations of this metering mode, their working principles are the same. The light intensity is measured according to the area pattern divided in the view frame, and these measured readings are analyzed and processed by the computer chip in the camera to determine the light intensity of the brightest and darkest parts in the shooting scene, so as to give accurate exposure readings and avoid exposure errors. The more divided areas, the higher the accuracy of photometry. This metering mode is an improvement compared with center focusing metering, but it is still difficult to accurately measure and expose under some extreme lighting conditions.

Spot metering: The biggest factor leading to exposure error in shooting is the bright or dark part of the shooting scene under extreme lighting conditions, which makes it difficult for the camera metering system to accurately measure light, resulting in overexposure or underexposure. The easiest way to avoid this situation is to measure only the most important parts of the scene, so that those bright or dark parts will not affect the lateral reading. Spot metering enables you to obtain metering values by measuring tiny parts in the viewfinder. This tiny part is usually surrounded by a small circle in the center of the picture, accounting for 1% of the whole image. As long as it can be used correctly, the spot metering system will be very practical and accurate, allowing you to accurately expose under most lighting conditions. Some cameras provide it? Partial metering? Or is it? Selective metering? Its working principle is the same as spot metering, but it is used in a slightly larger range of viewing frame metering.

Realization method of high-order exposure

Equipped with all kinds of metering systems mentioned above, you should be able to make an accurate exposure of 100%. But before that, you must remember a very important factor. Basically, all modes of photometry systems obtain exposure readings in a similar way. It is particularly important that all camera metering systems can calculate accurate exposure readings only when objects or scenery can reflect 18% incident light. Visually, 18% reflection means this medium gray color, so imagine what this medium gray looks like and keep it in your mind.

If you want to get accurate exposure by using the metering system on the camera, you must accommodate a certain range of tones in the object or scene you shoot, and their reflectivity is similar to and similar to medium gray. There can be bright and dark parts in the scene, but in general, it is basically equal to the middle tone.

Problems arise when the hue in the scene deviates from the middle hue, because it means that more or less than 18% of the light is reflected back. However, the camera can't distinguish these differences, and still set the exposure according to the average value, which will lead to errors.

In reality, this means that because your camera can't give enough exposure, scenes containing very bright scenes will be underexposed, for example, if there is a snow-covered landscape in the scene, or there is a bunch of white flowers in front of a dark scene. On the contrary, if there are very dark parts in the scene, such as objects in the sun facing the shadow-covered background, it will lead to overexposure, because your camera may give too high an exposure reading.

Similarly, if one part of the scene is much brighter than other parts, it will increase the reflectivity of the scene and make your camera's metering system give an underexposed reading. This is a common problem when taking landscape photos, because the sky is much brighter than the landscape itself. So, if you don't take measures, your photos will be underexposed, at least in the landscape.

If you are faced with such a situation, the easiest way to eliminate the exposure error is to use your camera to measure a comprehensive reading through centralized metering or area metering, and then increase or decrease the exposure through the exposure compensation device. The exposure you need to adjust depends on the scene you shot and how dark it is in how bright. In addition, due to the performance of different camera models in different lighting conditions. You may find that it has a good performance in some cases, and it only needs a little adjustment to produce perfect exposure.

The following table shows some examples of exposure adjustment when using center offset metering.

Object exposure adjustment

Snow scene in bright sunshine+2nd gear.

Cloudy snow scene+1.5.

White objects fill photos +2 files.

Small object facing white background+2nd gear.

Large object facing white background+1.

Scenery under clear sky+1~3 files

Silhouette facing the sun+2nd gear.

Small objects on black background-2nd gear

Large object facing black background-1 gear

Black Object Filled Photo -2 files

The exposure adjustment in the table can only be used as a reference. It is recommended to take more photos, each with a slightly different exposure, so as to ensure that at least one photo is accurate. For example, if you shoot a snow scene in the sun, increase the exposure according to the following amounts on the basis of the original exposure:+1,+1.5, +2, +2.5 and +3. This technique is called step exposure. It looks like a waste of film. But this is not the case. Taking four or five photos of the same scene, two of which are acceptable, is much better than taking only one but the effect is very poor.

If you want to avoid underexposure caused by bright sky when shooting scenery, then a useful trick is to tilt your camera down to exclude the sky from the picture. At this point, read the exposure readings and set up your camera manually. Then re-compose and shoot.

Two examples:

Equipment: Nikon f 90 prof. Camera, 105mm lens, polarizer.

Film: fujifilm ISO50 exposure: 1/30s, f/ 16.

Because the dark sea surface accounts for nearly 90% of the photo width, it is easy to cause overexposure. Because the dark tone only reflects a little light, the camera's metering system wants to record according to the middle tone, which leads to overexposure. In order to avoid this situation, the photographer reduced the exposure by two levels on the basis of the side exposure reading through the exposure compensation device of the camera.

Equipment: Nikon f 90 prof. Camera, 28mm wide-angle lens, 8 1C warm color filter.

Film: fujifilm ISO50 exposure: 1/30s, f/ 1 1.

Be careful when shooting in the sun, because bright sunshine and sky will lead to serious underexposure of other scenes. When the scene is covered with snow, the danger is even greater. In order to get a good photo with correct exposure, the photographer took photos with +0.5,+1,+1.5, +2 and +2.5 files respectively on the basis of the measured exposure number. All the photos taken are acceptable, but after comparison, it is found that the effect of +2 file is the best.

Point of use metering well

If your camera has a photometry (or partial photometry/selective photometry) device, use it to measure the light intensity of the most important part of the scene, so that the light or dark parts of other parts will not affect the obtained photometry reading, thus avoiding exposure errors. For example, if you measure the light of a person standing on a white wall like this, the white wall will not have any effect on the photometric reading at all, so this person can be exposed correctly.

This is an effective method for accurate exposure under subtle lighting conditions, but when using it, you must remember that you are still measuring the reflected light, so you still need to measure the reading in the mid-range area. If you don't do this, but measure from a part that is too bright or too dark than the mid-range area, then you will get the wrong reading. Fortunately, in most scenes, it is very easy to find the key part in the middle. When shooting scenery, green grass is an ideal middle-tone scenery. Stones and bricks, slate tiles, gray clothes and other things with similar colors eroded by wind and rain can also give accurate exposure readings. The key is to find something similar in color and density to medium gray.

Spot metering can also give accurate exposure when the contrast between light and dark is very strong. In this environment, the bright part of the scene is so large that it is difficult to record it completely on film. All you have to do is choose a spot from the brightest part for spot metering, then choose a spot from the darkest shadow part for spot metering, and then use the average of the two as the final exposure. For example, the exposure reading given by highlight is f/ 1 1, the shutter time is 1/500s, the exposure reading given by shadow is f/ 1 1, and the shutter time is 1/30s, so take the average of the two, and the aperture is f.

Subjective exposure

Of course, it is important to know the correct exposure in various environments, but? Correct exposure? However, there are many explanations for this term, and the best exposure of a photo is not necessarily the exposure value that is generally believed to be correct. It is the exposure result that conforms to the photographer's supervisor's wishes.

Step exposure

Perhaps the simplest and most effective way to avoid exposure errors is step-by-step exposure technology. This technique is to shoot the scene with the exposure value that you have measured and think is correct, and then increase or decrease the corresponding exposure according to this value to shoot the same scene.

The easiest way is to use the exposure compensation device on the camera, which allows you to take exposure readings far away from the measurement. Most single-lens reflex cameras have this function. The latest models of cameras enable you to correct the exposure in increments of 1/3, 1/2 or full range or reduce it to five levels by pressing a button or turning the dial. Some cameras even have automatic step-by-step shooting settings. When using this function, the camera can automatically take a series of photos with different exposures.

The exposure range of step-by-step shooting depends on the slight change of light conditions in your shooting environment and the film you use. As mentioned above, color negatives have a high tolerance for exposure errors, so it is absolutely unnecessary for color negatives to shoot step by step in increments of less than a complete file. But for color slides, because of the high exposure accuracy, it is best to use 1/3 file. Or 1/2 as the increment of step shooting.

In most cases, it is enough to take three photos at a time. One was taken with the measured exposure value, one was higher and the other was lower than exposure value. The exposure increment is 1/3, 1/2 or 1. Of course, if you know exactly the dangers of overexposure, such as shooting a scene full of dark tones, then you only need to take step exposure shooting to reduce exposure value. Similarly, if there is a risk of underexposure, such as shooting a snow scene with a bright background, you only need to take step-by-step exposure shooting to increase the exposure value, and the opposite direction is not allowed.

Step-by-step exposure shooting is undoubtedly a very useful technique, but you should only use it when necessary, otherwise you will find that your film will be used very quickly.

Now you know how to avoid underexposure caused by bright background in photos. However, in some cases, errors may occur, such as when you want to create a profile.

So, when you master the technology and know-how of advanced exposure, don't be afraid to ignore it sometimes, or at least adopt a few principles according to your needs. In the final analysis, the purpose of exposure is to ensure that there is enough light shining on the film in the camera to take the photos you want. Only you know how to do it.

Use a hand-held exposure meter.

In many environments, the fastest and easiest way to get accurate photometric readings is to use a hand-held exposure meter. The working principle of this exposure meter is the same as that of the metering system in the camera. It can also give exposure value by measuring the light reflected from the scene, and can also give a reading by measuring the incident light falling on the object or scene. The biggest advantage of this method is that the reading obtained by measuring the incident light will not be affected by the bright or dark parts in the scene, so the hand-held exposure meter can always give accurate results anyway. Most experienced photographers use hand-held exposure meters.

In order to get the reading of incident light, in front of the subject, point the end of the white measuring circle of the hand-held exposure meter at your camera, so that the light falling on the subject can be measured. For example, if you want to take a portrait with the window as the light source, you need to place the exposure meter a few centimeters away from the subject's face, aim the back end of the exposure meter at the camera position, and then press the measure button to get the exposure value. Even if there is a very bright window behind your subject, your reading will still be very accurate, because the exposure meter only measures the light that falls on the subject's face, but if you use the metering system on the camera to measure the light, the bright window will inevitably lead to underexposure.

If it is difficult to get close to your subject, for example, when taking a landscape photo, point the white measuring end of the exposure instrument behind you and let the light falling on the scene also fall on the light meter.

The only place that is not suitable for obtaining the exposure number by measuring the incident light is when the light you need to measure is not within a range. For example, when you need to take a landscape photo, the distance of the scene is illuminated by the sun, and you need to expose that part of the scene. The reading of incident light can measure the light intensity around you, which is quite short compared with the scenery illuminated by sunlight in the distance. So at this time, you need to use spot metering to measure the part of the sun. Many hand-held exposure meters can be equipped with spot metering for this purpose.

Special reminder: unlike using film, the nominal sensitivity of digital cameras is sometimes not necessarily accurate. When using a hand-held exposure meter, you should first understand the deviation of the nominal sensitivity of your camera.

Secret of success

In subtle lighting conditions, you can avoid exposure errors by preventing 18% gray cards from appearing in front of the subject, and then metering these cards to obtain metering readings. These cards can be bought in most photographic equipment stores. Generally, there are 2~3 sets of cards of different sizes, so you can take one set in your own accessory bag for backup.

It's a good idea to write down exposure value when shooting in dim light. You can compare your notes with the photos you get. If you find that the shooting failed due to an exposure error, make sure that you won't make the same mistake again.

Consciously underexposed the color slides from 1/3 to 1/2 can increase the color saturation.

When using color slides, highlights are usually exposed, regardless of shadows; When using color negatives, to record the details of shadows, highlights can be enhanced in the development stage.

Equipment: Pentax 67 camera, 165mm telephoto lens,

Tripod, cable release, holding Pentax digital spotlight exposure meter.

Film: fujifilm ISO50 exposure time: 30 seconds, f/ 16.

In this photo of Eilean Donan Castle in the Highlands of Scotland, the castle illuminated by floodlights is not only the key feature, but also the brightest part of the whole landscape. Using the total luminosity reading will lead to overexposure of the castle, because the surrounding landscape knowledge is illuminated by the afterglow of the skylight reflected by the water surface, which is quite dark. In order to avoid exposure error, based on exposure value: 20s and aperture f/ 16, step exposure was carried out, and the exposure amounts were: aperture f/ 16, 10s, 15s, 20s, 30s, 40s and 60s respectively.