By F. M. Kearney
In the days of film, accurate metering was a big headache for many beginning photographers. It was even worse if you were shooting color slide film. Unlike color print film, which often had color and exposure corrected by the processing lab before the prints were made, slide film was much less forgiving… what you shot was what you got. My film of choice was Fuji Velvia ISO 50. It’s a highly-saturated, fine-grain film and perfect for nature photography. Its only downside is that it has very little exposure latitude – meaning that if your exposure is off by just a stop or two, your highlight and/or shadow details might be completely lost. My normal workflow was to take multiple meter readings of each scene… one of the highlights, one of the mid-tones and one of the shadows. I’d then do a quick mental calculation to determine the best exposure for the subject – usually a totally different setting from any of the readings I just took.
That may sound like a lot of work, but it all became second nature after a while. Fortunately, digital technology has made things much easier… especially if you shoot in Raw. Your exposure could be off by as much as about 5 stops and you’ll still be able to get a good image in post-processing. Additionally, some camera models are even equipped with features that increase the dynamic range of their sensors – the ability to see more details in the highlights and shadows. Personally, I think that’s one of the biggest benefits of digital over film. With all of these advances, you might think that metering is something you no longer need to be concerned about. While that may be the case under “normal” lighting conditions, there are certain situations where a basic understanding of metering is not only helpful, but necessary.
How in-camera meters read scenes
The thing to keep in mind is that no matter how important the subject of your photograph may be to you, the meter in your camera couldn’t care less. That’s because camera meters don’t “see” specific subjects, but rather overall tones. They are designed to give you a middle-grey value of everything you shoot. This means that they don’t want to set an exposure that’s too bright or too dark, but somewhere right in the middle. In most cases, this may be exactly what you want. But, what if your subject actually is very light or very dark? Blindly following the meter’s recommended setting will result in an incorrect exposure. If your subject is very light in tone or color, you will need to override the meter and slightly overexpose. Conversely, if your subject is very dark, you will need to lean towards underexposure.
When I first learned about metering, I thought that that was the most counter-intuitive thing I had ever heard! If you add more exposure to something that’s already bright (or less exposure to something that’s already dark), wouldn’t that just cause an extreme over- or underexposure? To better understand this, let’s set aside aperture settings and shutter speeds for the moment and deal with real-world numbers. The scale below shows a range of tones from 1 to 10, where “1” represents pure white and “10” represents pure black. A middle-grey value would be at about a “5” – the default setting of a camera meter.
Now, consider a typical snow scene, such as the images below. Referring to the tonal scale, you will see that the overall tone of the image on the left closely resembles that of a “5” – the meter default setting. The meter sees a scene that appears to be too light. As a result, it wants to bring it back to the middle of the spectrum. A middle-grey value may be perfect for a scene depicting a field of green grass under a clear blue sky. But, if you’re shooting a snow scene that’s predominately white, and you want to keep it white, you will need to ignore the meter recommendation and lean towards overexposure. The image on the right is a much more accurate representation of the actual scene. I had to overexpose it by 2 stops, bringing it to a tonal value of around a “2” on the scale – a gross overexposure for most scenes, but perfect for this one. You can override the meter either by shooting manually, or by using your exposure compensation control – designated by a “+/-” symbol. How much you override it in either direction is totally dependent on the image, and best determined by bracketing one stop at a time.
As with most things in photography, this is subjective. I made a point to mention that it’s only necessary to deviate from the meter’s recommendation if you want to keep the scene white. Snow scenes can convey quite different moods. A very bright image will suggest a joyful and playful mood, while a darker image might signify “doom and gloom.” So, it’s really dependent on your own artistic vision how you choose to expose the scene.
Dealing with high contrast
Extreme lighting conditions are another challenge for in-camera metering systems. The photo above is a typical example of a high-contrast situation. The proverbial light at the end of the tunnel is obviously much brighter than the tunnel itself. And if that light is your subject, it’s going to be overexposed if you follow the meter’s recommended setting. Remember, the meter doesn’t know what your subject is… it just sees a tone that’s predominately dark, and it wants to lighten it up. In the process, though, it completely overexposes the much lighter subject.
The problem is caused by the fact that most meters take an overall reading of the entire scene and give preference to the most dominant tone. To overcome this, you can switch to your camera’s spot meter. As its name implies, it only reads a small spot of the overall scene and ignores everything else. In the image above, I spot metered the opening at the end of the tunnel. That gave me the correct exposure for the opening, but I lost all detail in the tunnel.
Benefits of digital technology
Sometimes, heavy contrast can be very dramatic. But what if you want to retain detail in both the highlights and the shadows? This has been a major problem for photographers ever since the creation of photography. With film, the only thing you could do was to bracket your exposure until you reached the “sweet spot” – the point where an acceptable amount of detail is retained in both the shadows and the highlights. Unfortunately, this type of compromise only results in neither looking their best. Luckily, with digital technology, you no longer have to settle for second best. You can get the best of both worlds by simply combining the photos in a digital editing program. The photo below is a digital combination of the two photos above. This was a fairly simple exposure blend. However, for more complex situations, you could shoot several images at different exposures and combine them afterwards in an HDR (high-dynamic range) program. You have far more options for dealing with difficult exposure problems today than you ever did with film.
Digital technology has made it easier to deal with the majority of metering issues of the past, but it hasn’t addressed all of them. Knowing how and when to override the meter will help you get the shot you want… not what your meter wants.
F.M. Kearney began his career as a photojournalist for a variety of local New York City newspapers. It was an exciting profession, which allowed him to cover everything from famous celebrities to ride-alongs with NYPD and FDNY. He now specializes in nature and urban landscapes. To view more of his work, visit www.starlitecollection.com. He can be contacted at firstname.lastname@example.org, or followed on Facebook (@fmkearneyphotos) and/or Twitter (@fmkearneyphoto).