Newbie Corner – Understanding Camera Meters

Newbie Corner – Understanding Camera Meters

There are two types of meters, incident and reflective. Incident meters measure the surrounding light falling on the meter. Reflective meters measure light reflected off a subject. The meter in your camera is a reflective meter.

Metering Modes:

Nearly all cameras today have automatic metering modes in addition to the manual metering mode. There are usually three auto exposure modes. They are:

Aperture Priority: You choose the aperture, and the camera chooses the appropriate shutter speed for the exposure.

Shutter Priority: You choose the shutter speed, and the camera chooses the appropriate aperture for the exposure.

Program: The camera chooses both shutter and aperture. You have very little control. We do not recommend using the Program mode.

Different cameras have different ways of indicating a “correct” exposure. Some use a match-needle method. Others use LEDs to indicate under, over, and correct exposure. Still others, mainly new cameras utilizing LCD displays, use an analog scale that shows a plus and minus range. (See the illustration below.)  Here zero means “correct” exposure and the plus side means the image is “over exposed.” Likewise, the minus side means “under exposed”.

        +2              +1              0             -1             -2

Nikon meters have a scale similar to this. Consult your camera manual to understand how your camera indicates “correct” exposure.

Most new cameras also give the photographer a choice of metering patterns. These include spot metering, center-weighted metering and evaluative, also known as matrix, metering. Be sure to read your camera manual so that you know how to set and use your metering system.

Spot meters, as the name implies, sample a very small portion of the viewfinder. Using a spot meter you can evaluate an entire scene and precisely control exposure.

Center weighted meters evaluate the entire viewfinder, with most of the measurement coming from the center portion. Depending on your camera, this center portion is given about 75 or 80 percent of the “weight” in determining the exposure, with the other 20 to 25 percent coming from the rest of the frame. In some cameras, you can specify this percentage via a custom function.

Evaluative, or matrix, meters divide the entire scene into zones and evaluate the relative brightness between different sections of the scene. Then, using proprietary algorithms, the camera determines the “best” exposure for the situation.

As we stated earlier, the meter in your camera is a reflective meter. Not all subjects reflect the same amount of light, however. For instance, a snow bank reflects much more light than a black bear. The meter in your camera doesn’t know how dark or light your subject is, or, more importantly, how dark or light you want your subject to be. Therefore, camera manufacturers calibrate in-camera meters to render a scene or subject as a medium tone, or what is called18% reflectance. Medium is halfway between black and white – it’s average. You may have heard of a gray card. A gray card reflects 18% of the light that hits it. A gray card is medium toned.

The meter in your camera assumes that everything reflects an average, or medium, amount of light. If you point your camera at a subject and adjust your settings until the meter is “zeroed,” meaning the indicator is pointed to zero or whatever the “correct” exposure indication is for your camera,  your subject will be rendered a medium tonality on film or digital sensor. If your scene has an overall medium tonality, the camera’s meter will generally work just fine. But if your scene is brighter or darker than medium, or if there is a wide range of lighting, then trusting your camera to determine the correct exposure often won’t work.

If your subject is lighter than medium and you let the camera’s automatic exposure mode choose the exposure, the subject will come out looking medium. If you’re photographing a field of snow and letting the camera decide the exposure, it will make that white field of snow into a medium (or gray) field of snow, creating a picture that looks dark and dingy. This is why the pictures you took on that snowshoeing trip look so dark.

This will seem counter intuitive, but you need to “overexpose” light toned subjects and “underexpose” dark toned subjects. In other words, change your camera settings until the meter indicates you’re over or under exposing, depending on your subject. Many wildlife subjects are medium toned, neither light nor dark. However, some are not medium toned.

For example, if you want to make a picture of an arctic fox, consider this:  Arctic foxes are white and their native habitat is snow. Since we know snow is much lighter in tone than medium, you’ll need to “overexpose” it to make it come out lighter than medium. We’ll be getting to how to determine the amount of overexposure, but for now, we want you to understand the concept of needing to overexpose white subjects to make them white.

If you adjust your camera controls so that the meter indicates “0”, the subject will come out medium. If you set your controls so that the meter indicates +1, then the subject will come out one stop lighter than medium. Notice we said one stop lighter than medium, not one stop lighter than the subject really is. This is where people get confused. Beginners often think that by setting the meter to +1, the subject will come out one stop too light. No. It will come out one stop lighter than medium. Let’s say the subject really is one stop lighter than medium. Then the photo will come out with the subject looking like you remember. However, if the subject really is medium toned, then setting the meter to +1 will over expose the subject, and it will look too light.

Learning the tonalities of subjects in the natural world, and exposing for those tonalities, will give the results you want.

In general, you need to add light (over expose) for light-toned subjects, and subtract light (under expose) for dark-toned subjects. Deciding just how much just requires practice. The following are some tonalities found in the natural world. Use these as guidelines to get you started.

Yellow leaves (fall color): +1 (yellow is generally about one stop lighter than medium)

Yellow flowers (daffodils, etc.): +1

Orange flowers, pumpkins: generally medium (0)

Bison: -1 to -1 1/3

Green grass: -2/3 to medium (0) depending on the season.

Dry grass: +2/3 to +1

Tree bark: generally medium (0)

Deer (most any species): medium (0)

Evergreen trees: -2/3

Snow: +1 ½ to +2

Reds: medium to –1 depending on how deep the red is

Desert sand: generally +1

Mountain Lion: medium (0)

Palm of your hand: +1

Sandstone (arches, rock formations, etc): medium to +1, depending on the kind of sandstone.

When photographing in even light, if you correctly meter one tonality, all the rest will fall into place. This means if you have a medium animal standing next to bright yellow autumn foliage, you can either meter the animal and set the meter to “0” or meter the foliage and set the meter to “+1”. Both methods will yield the same setting and same exposure.

As stated previously, these are general guidelines. Once you learn a few of these you’ll be able to recognize different tonalities and transfer them to the wildlife you are photographing. For instance, deer are medium in tonality. For the most part, so are elk. Elk often have a dark rump though, and you have to be aware of that.

We’ll address some other wildlife specifics later.

This graphic gives you a general idea of what the tonality of your subject will be when you set the meter at a given point.

Screen Shot 2020-02-25 at 4.39.35 PM        

If you point your meter at something and set the camera so that the meter indicates +2, the subject will come out white. If you set the camera so that the meter indicates –1, the subject will come out dark. If you’re photographing snow, you’ll want to use between +1 ½ and +2. Are you getting the idea yet? Try to decide how you want your subject to look on film. If you want it to look as it does in real life, just adjust your settings until the meter indicates that your subject will have the same tonality on film that it has in reality. This will take some experience. Use some of the tonality guides listed above as a starting point.

If your camera doesn’t have a handy indicator in the viewfinder to tell you when you’re at + or –1, set your camera controls until the meter indicates that you have “correct” exposure. This will render whatever the meter is pointed at as a medium tone. Once you get to a starting point, you can make the adjustments for the tonality you wish. If you’ve determined something is one stop lighter than medium, then begin by setting the meter so it reads medium. Then open up one stop by either choosing an aperture that is one stop larger (equals a smaller f-stop number) or use a shutter speed that is one stop slower. Either one works by letting in one more stop of light.

For the greatest control over the exposure process, use your camera’s spot meter in the manual exposure mode.

Here’s a valuable exercise: Spot-meter everything you can in a scene. Start by finding something you think is medium and adjust your shutter and aperture controls (in the manual mode) until the meter indicates “correct” exposure (“0” on the above scale). Now, start looking at the rest of the scene without changing any of your settings. Watch your meter’s indicator move up and down (+ and -) while you pass over different parts of the scene. What happens when you place the meter on something light or white? How about when you place the meter on something dark or black, such as a shadow?

What you’ll see is the meter’s indicator moving up and down depending on the tonality of the object the meter is reading. With this information, you’ll be able to tell just how all the elements in your composition will turn out in the final image. You don’t even need film in the camera for this experiment. Just point the camera at differently toned objects and see what happens, see how they relate to one another on the exposure scale. When you do this exercise, pay particular attention to those objects that read +2 or brighter and -2 or darker. These are the objects that won’t be rendered well on film.

Picture Methods has partnered with Hunt’s Photo & Video to bring you the best gear at a competitive price and backed by personal service. Call Alan Samiljan at 781-462-2383 or Noah Buchanan at 781.462.2356. If you cannot reach either one try Gary Farber at 781-462-2332. You will ALWAYS get the best prices if you call the store v. Using the web site. You can also email Noah at: or Alan at or Gary at: Hunt’s has been around a long time and you can trust them. Make sure to mention that Scott Bourne sent you. That will get you the best deal.

3 Responses

  1. That’s probably the best discourse on metering I think I’ve ever seen. Well done.

    I’ve been doing something different since I moved to mirrorless though, and I’d like to hear your thoughts on it.

    As we all know a mirrorless camera shows What You See Is What You Get (well at least most of the time). What I’ve been doing is to set my meter to matrix mode, mostly because it seems to average out me moving where I’m pointing the camera. I typically have my camera to show the histogram or more preferably the blinkies (highlight / lowlight warnings). If I’m shooting in A or S I use the exposure compensation to adjust the exposure to what I like visually for my subject. The histogram or the blinkies warn me if I’m clipping part of the scene, and I can adjust or just except it. I can also bump up the exposure to expose more to the right. This works particularly well for things like landscapes.

    I find this is a very quick way to handle exposure, and rarely am I off more than 1/2 a stop in post production.

    There are times of course where this technique won’t work all that well. Usually in those cases I’ve set the exposure to manual. A good example of this is with birds in flight, where I have determined the exposure for the bird in the available light. But the background varies from open sky to brush or trees, which would mess with matrix metering. But since the light is relatively constant, an exposure for the bird will remain constant so long as they don’t fly into the shadows.

  2. I have read numerous articles on metering. Your explanation is SPOT ON point in my opinion. Great article!

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