Reflective metering merely just tries to keep the average of all the tones more in the middle, not too dark, and not too bright. It is a silicon chip, not an experienced human brain that can think about what it sees. It cannot differentiate between dim white vs. Metering on an 18% gray card (in that same incident light) makes a reflected meter mimic an incident meter (reading the incident light, independent on subject colors).Ī reflected light meter (camera meters are reflected meters) cannot try to recreate the correct tones, because it only sees a blob of light, and it cannot recognize anything to know what it means, or how it ought to be.
Incident meters instead work very differently (examples on the third metering page), more correctly metering the actual incident light on the subject instead of the reflected light (which is affected by the subject colors). That's all a meter can know to do, without a human brain and experience to be able to recognize the scene, to know how it should be. So the only possible goal is a result not too bright, not too dark. We would think that a dark scene ought to look dark and a bright scene ought to look bright, but the meter cannot distinguish them. As the background becomes more white, the blob of light appears brighter, so reflective meters underexpose it, still trying to achieve the same overall (middle gray equivalent) average result for the area (the averaged colors of rose and background). In the first picture, the black is overexposed towards middle gray. This average tone of all such properly metered scenes can only go near the middle range. It can measure the light, but it sees the averaged tone blob in the area it sees. But the meter has no brain, it just sees a blob of light with no clue what anything is, or what it means, or how it ought to be. Our human brain and experience can immediately recognize the scene, and we know exactly how it ought to look. Which includes the rose, and some of the background. The flash TTL system meters on its fixed central area. A reflected meter puts (the average of) everything in the middle. The meter does not know what anything is, or how it should be. The exposure sets that to be a middle result. The exposure sets that to be a middle result.ĭark colors reflect less light to meter a low value. Light colors reflect light well to meter a high value. Not everyone can be bothered to think, but photographers learn this. It does require a quick look and thought about the picture you're about to take. The general rule is that low reflectance dark colors tend to overexpose, and highly reflective light colors tend to underexpose. Reflective metering exposure depends on what you aim it at and how well it reflects light. This is what happens, how reflective metering works, on your camera too. This is the reason some users meter on an 18% gray card (in the same light as on the subject). The scene that does actually average to a middle gray is metered more accurately. See? Both the predominately dark scene and the predominately bright scene are exposed to be a gray scene. The ONLY change in each frame is that the black background was simply moved left after each picture, so that the camera TTL metering saw more white paper.
LIGHT MEETER ISO
No cropping, ISO 200, all f/8, 1/200 second, TTL. This is how reflective metering works (it sees the light reflected from the colors in the scene).ĭirect flash, on cord off camera. The exposure you get depends on what the meter sees. Then the TTL metering reacts to the new scene it sees. The scene the meter sees is different, different ratios of dark and light colors. To make that be real clear, let's adjust only the background scene a little at time, all else stays the same (but still with automatic TTL metering of the flash).Īt each frame, the ONLY difference was that the black paper was shifted left a little, and then the shutter button was pressed again. Under or over exposure depends on the scene the camera sees.Īll of this page is speaking only about reflected meters, like are in cameras (two more pages to Incident meters). However, the camera's reflective light meter sees different scenes differently. The camera is aimed at the subject, and TTL automation exposes the picture. VWR will support you from the latest life science products to the guaranteed purity of organic building blocks.The ONLY difference in these next pictures is that the background scene is modified (ordinary white and black craft paper, just shifted to the left).Īll else is the same. A strong, vibrant research and development group is the lifeblood of all industries.
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