This is a question I'm often asked about, so here's the explanation:

ALL in-camera exposure meters are "Reflection" meters, meaning that they read the light reflected by your subject(s) - as opposed to the light falling on your subjects - as do handheld exposure meters. This wouldn't be so bad if they read ONLY the light reflected by your subject; but they read ALL the light coming in to your frame, including light from areas around your subject. Yes, they have sensors that enable you put more emphasis on certain areas of your frame, like "center-weighted evaluative metering," for example. And for many shots, these built-in meters work very well. And that's as good as it gets for most snapshooters or "point-and-shooters." But for photographers, it's not good enough. A photographer requires perfect exposure for virtually every shot, no matter what the circumstances may be. A photographer is paid very well to get perfect images. For some great images illustrating how and why we all need a meter, please don't you DARE miss this!

The best solution to this problem is for the photographer to own a good handheld flash-ambient-spot meter (I don't sell meters, so I can be 100% honest about the suggestions I make here). But whether or not he or she has a handheld meter (like the Sekonic L-508), s/he needs to understand how meters work, so s/he can achieve perfect exposures no matter what kind of meter is being used. So now let's take a moment to learn how meters work.

As we've just learned, ALL meters built into cameras are reflected light meters, which means they read the light that's reflected by your subject (and areas surrounding your subject), rather than the light falling upon your subject. Much of the time, using sophisticated computer chips to analyze the reflected ight, these built-in meters do a pretty good job. But for many other circumstances (backlighting, very light or dark subjects, bright and/or dark areas of the frame, etc.), these meters fail us. Why? Well, there's a two part answer: one part is because we don't understand how to properly use our built-in meters, and the second part is because ALL built-in meters are geared to 18% gray.

What's "18% gray?" you might ask? Well, the scientific gurus have determined that the average reflectance of the average scene is 18% gray (some of the latest research indicates it might actually be 14% gray, but that's just splitting hairs). Why a "normal" scene reflects 18% gray might be fodder for physicists to discuss, for our purposes, just accept it. And anyway, every meter in every camera is keyed to 18% gray. That's just the way it is. And, for this discussion, we'll speak of black and white photography (because it's easier to understand), but pretty much the same problems occur in color photography too, and the same solutions also result in us getting perfect color prints, slides, and negatives.

Now, IF the scene you're photographing IS a perfect 18% gray, wonderful; you'll get a great exposure. But in real life, some things are white, and some things are black, and some things varying shades of gray (or color). So if we were to take a picture of a snow-covered field, and let our camera's meter set our exposure for us, the print will come back with the white snow reproduced as gray. On the other hand, if we were to take a picture of a big pile of jet-black coal, and let our camera's meter set our exposure for us, the print will come back with the black coal reproduced as gray. Why? Because ALL meters are keyed to reproduce 18% gray! Hmmm. Why? Because MOST scenes reflect 18% gray, and so that's as close as the scientists can get to a thinking camera. It's better than a dumb camera, but it usually results in acceptable results for most of the snapshooter's pictures. For some pictures showing this subject, see here: http://myphotohome.com/mtrg/

What can we do to assure that WE get proper exposures for OUR pictures? There's two ways: one, and the best solution, is to get a good handheld exposure meter; and two, is to learn how to "trick" our built-in "dumb" reflection meters into setting the correct exposure for us whenever we're photographing a challenging scene.

Why are handheld exposure meters so much better than meters built in to our cameras? Because the handheld exposure meters don't read the light reflected by our subjects (and everything surrounding our subjects, too); they instead read the light that's falling on our subjects! Consequently, the handheld exposure meter can tell us exactly how much light is illuminating (falling upon) our subjects.

Why is this important? Well, dark colors don't reflect much light (they absorb more light), and light colors reflect (bounce back) more light, so a meter reading the light reflecting from our subjects is easily confused by the different amounts of light it's reading, and sets our exposure incorrectly in many instances. But a meter that reads the amount of light falling upon our subjects, can't be confused by the different amounts of light reflected by lighter and darker subjects, and consequently can tell us exactly how to set our exposure for virtually perfect pictures every time.

With a handheld exposure meter telling us how to set our exposure, snow will come out perfectly white, coal perfectly black, and everything else exactly as it appears to our eyes (within the limits of the film (or CCD) and paper the pictures are printed on, of course). So, the easiest solution is to get a good handheld exposure meter. BTW, a handheld exposure meter is placed right in front of, or right next to, your subject, pointed directly towards your camera, and then the reading is taken (push the reading button on the handheld exposure meter, and it responds with proper settings, and allows you to choose ANY available combination of apertures, shutter speeds, and films, and automatically calculates and gives you proper settings for any of the variables! This allows you to "ask" the meter: What if I want to use a larger or smaller aperture (to control depth of field)? or, What if I want to use a faster or slower shutter speed (to control movement)? Most handheld exposure meters will also take several readings, from different parts of your subjects (such as sunlit and shadow sections of a landscape, for example), and will average them for you to achieve proper exposure).

Next, let's learn a couple of ways to "trick" the reflection meters built-in to our cameras into giving us good exposure settings for almost all our shots. Remember I told you that ALL meters are keyed to 18% gray? OK, so how do we trick a reflected-light meter into giving us perfect exposure settings? The easiest way is to buy a "Kodak Gray Card." They usually sell for under $10.00, so it's something we can all afford. What is a "Kodak Gray Card?" It's a piece of cardboard that's printed gray; 18% gray, to be exact! Hmmm. What good is it to us? Read on.

How do we use a "Kodak Gray Card" to get proper exposures with our built-in meters? Here's how: hold the gray card in the same light our subject is in (e.g., if our subject is a person standing in the sunlight, we hold the gray card in the same sunlight as the subject - in other words, don't hold the gray card in the shade of a tree to take the reading, hold it in the sunlight; conversely, if our subject is standing in the shade of a tree, we should hold the gray card in the same shade to take our reading). OK, now, hold the gray card in the same light our subject is in, tilt it to about a 45º angle, point your camera at the gray card, and fill your finder (looking through the camera's eyepiece, fill your whole frame with the gray card), and then take your exposure reading. Lock in this exposure reading... on many cameras, pressing the shutter button half-way down will lock in the exposure for you... and then recompose your shot (without releasing the shutter button, or other device your camera uses to lock exposure - see your manual - aim your camera at your subject, focus, and shoot the picture! This "tricks" your built-in meter into "reading" the light falling upon your subjects by reading the light reflected by the 18% gray card, and giving you perfect settings.

Since the gray card is a perfect 18% gray, and the camera's meter is keyed to 18% gray, if we make the meter read the light reflected by the gray card (instead of the light reflected by our subjects), we're "tricking" our meter into reading the light falling on our subjects, rather than the light reflected by our subjects. Get yourself a gray card (sorry, I don't carry them), and then you'll be getting much better pictures. We can't make our meters "smart," but WE can become smart enough to "trick" our (relatively) dumb built-in meters into giving us perfect exposures.

But what if we don't have a handheld meter or a gray card (yet:)? Here's a few alternatives we can use:

1) Instead of letting our camera's meter read the light reflected by our subjects AND everything else in our viewfinder, either zoom in to fill the viewfinder with our subject (i.e., the face of our subject, or the flower's petals, or the black cat's coat, etc.), or, if you're not using a zoom lens, walk up close to our subject, fill the viewfinder with the most important part of our subject (i.e., the face, etc. as described above), then, when our viewfinder is filled with our subject and NOT with the surroundings, lock in exposure (e.g., press the shutter button half-way down), and zoom out or back up, re-compose the shot, and then press the shutter button all the way down and make the exposure! I think you'll be amazed with the results!

2)Instead of letting our camera's meter read the exposure from our whole frame, set your built-in meter to its "spot" setting. Then, center the most Important part of your subject (i.e., the face of a person, the petals of a flower, the coat of a dog, etc.) in your meter's spot circle and take your reading; then, when our viewfinder's spot circle is filled with our subject and NOT with the surroundings, lock in exposure (e.g., press the shutter button half-way down), re-compose the shot, and then press the shutter button all the way down and make the exposure!

3) If we can't use any of the above techniques for some reason, then try this: If your subject is a person with a skin tone similar to yours, take a reading off your own hand (but be sure to hold your hand in the same light your subject is in), lock in the exposure, recompose your scene, and shoot. Another possibility is, if you're outdoors, and your subject is an outdoor scene, you can take an exposure reading off the grass (in the same light as your subject), since a normally-green lawn is often close to normal reflectance (18% gray).

Of course, these techniques will only work in available light photography and digital/video continuous lighting equipment; if we're using a flash or pro strobes, we can't take readings off gray cards or substitutes; for flash photography you'll need a flash meter. For some great images explaining how and why we all need a meter, please see this: http://myphotohome.com/mtrg/

Now that we understand how our in-camera meters work, we'll be able to make the right decisions about making the proper exposure settings.

Well, folks, I hope this helps; if not, just let me know, and I'll try to offer some additional suggestions for you.

-Richard

photosource3 on eBay

© 2006 R. Morgan • All rights reserved