When reading photography books or articles, you would definitely come across expressions like ‘I aimed my camera at the sky and then metered or I would meter the face etc.’ I don’t know about you, but I used to get so confused at these explanations, when I was learning to use my camera and the science behind metering. It took me some time to figure out the details, and once I learned to use manual metering, I found it very easy and useful. This article is an attempt to explain the basic metering principles, and techniques involved in manual metering.
As explained in a previous article (A Case for Manual Metering), your camera sensor is programmed to relate everything it sees to 18% gray, in order to make the exposure decision. All the auto or semi-auto settings are trying to achieve the perfect exposure based on this principle, combined with the metering scheme selected. With full auto, the metering is defaulted to “matrix’ or ‘evaluative’ scheme.
Every photographer, at some point in their photographic journey will be using manual metering; some of us, way early and some of us, a little later (usually with a little pat and push from the back). My job here is to give that little pat and push, if you are still sitting on the sidelines watching the fun. This article has 2 parts, in part -1, we will refresh our memory on the metering modes and how the metering works with your camera. Part 2 will be dedicated to the manual metering techniques.
You can’t learn to swim without getting into the water; you can’t learn to ride a bike at a seminar; you can’t learn to yell without being yelled at… right? (The last one, I just made up). But the point here is that, ‘attempting is the first step in learning’. So here is what I want you to do, read this article (and it’s part 2) carefully, try out the steps explained and come back and tell me, if that worked for you or not.
The choice of metering mode (Matrix/Evaluative, Center Weighed, Partial(Canon only), or spot) is really dependent on the scene that you are going to capture. Before explaining the ‘how’ part of manual metering, let’s refresh our memory on the metering modes.
Matrix/Evaluative metering has evolved in the last couple of decades and is generally very reliable. In matrix metering, the system uses the entire scene for the exposure decision. See below for Nikon’s own explanation.
“This meter gathers information from 1005 red, green, and blue sensors and factors in distance information provided by the lens as it evaluates proper exposure calculation. This meter instantly analyzes a scene’s overall brightness, contrast, and other lighting characteristics, comparing what is sees against an on-board database of over 30,000 images for unsurpassed exposure accuracy, even in the most challenging photographic situations. By the time the 3D Matrix meter has made its considerations of colors by hue and saturation, tonal ranges by brightest and darkest, areas of similar tonality that are connected or separated, distance to the subject, and compared that to its database generated from photographic images, it’s got a very good idea of what the exposure should be.”
Matrix or evaluative metering is the default mode in most of the cameras and it works just fine in most cases. But there are times when the metering system gets fooled by the subjects in the frame, such as a bright overcast sky, light bulb, predominantly dark or light areas etc. The problem in all of the above cases is that, the metering system won’t be able to guess the appropriate exposure for the scene (see the example in the article A Case for Manual Metering) and the output will be either too dark or too bright.
Center weighed metering work better, when you want to give priority to the center area of the frame. That doesn’t mean that the other areas are ignored, but the exposure decision will be biased toward the center of the frame. You will be able to change size of the center area from the menu setting of your camera.
Spot metering uses sports within the active focus points to determine the appropriate exposure. This is the case with Nikon at least. So it’s not just the spot in the middle of the frame but the spot(s) within the active focus points. This may sound a bit confusing, but that’s how it works. You can always use the center focus point and the associated spot, or you can change the focus points to another area in the frame and use the sport(s) within them. Check your camera manual for more details on this.
Partial metering (not available with Nikon cameras) similar to spot metering but it covers a little more area than the spot metering area.
When you shoot in P, A or S modes, your chosen metering mode plays a part in the camera’s exposure decision. Now, you might question the wisdom in metering a scene manually, when P, S and A modes can also make use of these metering modes. The difference is that, with any of these modes, the camera makes the decision for you and with manual metering; you make the decision on where to meter and what to mater on.
Remember, manual metering and manual modes are two different concepts. In manual mode, you select the shutter speed and aperture (and ISO) based on your expected outcome and with manual metering; you make the decision about the metering modes and the subject that you want to meter on. You don’t need to meter manually to use manual mode.
This concludes the first part of this article. In part -2, we will discuss the manual metering techniques in detail. If you want to receive notifications of new posts by email , you may subscribe to this blog by clicking the button on the right.
Please don’t hesitate to leave your thoughts and comments. Also, please let me know, if you would like to contribute more to this article.
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