Let's say that you are photographing a scene, perhaps a covered bridge in Vermont with white clapboard siding and deep shadows on the roadway. If you use an incident reading the dark shadows will likely lose detail, so you decide to compensate. But how much should you increase the exposure? One f/stop? Maybe two f/stops? That's all well and good, but at some point you'll begin to overexpose the white clapboard. So, like most photographers, you bracket the exposure like crazy in the hope that at least one negative will be printable. While this approach is very common, results are not very predictable and it certainly lacks craftsmanship. Now, let's approach the same challenging scene with a spot meter and a see how our technique will differ.

This magical lighting lasted just long enough for me to read the shadow area in the background and the highlights on the trunk of a nearby alder. With practice, and familiarity with your meter, spot metering can be accomplished very quickly.

First we make a reading of the darkest area in which we wish to capture some texture. The dark weathered wood a little way inside the bridge should work. There will be some areas that are darker, but that's all right, as we're interested in an area that we want to record with full texture.

Reflected meters are calibrated to make what they read a medium tone in the image. Many texts refer to this tone as 18 percent gray or middle gray. There is some controversy about the actual standard used, but suffice it to say that if you think of this tone as middle gray you'll be fine. In the Zone System this medium tone is referred to as Zone V (Zone 0 being pure black and Zone X being pure white). But Zone V, the equivalent to an 18 percent gray card, is too light for the shadow area we just read, so what do we do? Well, stopping the lens down one f/stop will make the shadow darker, or a Zone IV tonality, and stopping down an additional f/stop will place it on Zone III.

This scene presented itself as David Brooks and I were driving down California's Scenic Highway One. I barely had time to set up the view camera, meter, and make two negatives before it went away. The sound of Brooks' motor drive whirring in my ear didn't help my concentration either.

OK, I have now set or placed my exposure to achieve Zone III, the darkest zone with full texture, for the shadow area I selected. So now what? Well, I next read the lightest area that I want to record with some texture, perhaps the white clapboard, and if the meter indicates that it is on or below Zone VIII the scene will record with full texture. Light meters with zone scales or Zone System modes (more on that later) will save a little bit of finger and toe counting here. Now the Zone System is a bit more involved than my brief discourse but not all that much, really. The point is you can really see how much useful information a spot meter can give you in this scene, and in similar scenarios.

It would be easy in this situation to underexpose and lose all of the detail in the doorway. At the same time, overexposure would "block up" the highlights in the white clapboard. I metered into the doorway and placed it on Zone II as I just wanted a hint of detail. The image prints quite easily with minimal dodging or burning required.

Check The Chart
So, maybe you're starting to think that a spot meter might fit into your photographic toolkit. Well, if so, what should you be looking for feature-wise and how much should you budget? To help answer these, and a lot of other questions you'll come up with, I've included a chart that lists the current choices in spot meters, and some multipurpose meters that have spot capabilities. Some of these meters read ambient light only, while the multipurpose meters offer spot and/or incident capabilities for ambient and flash photography, a valuable feature if you do any studio photography. A few years ago I started using a multipurpose meter and I have found it very convenient to have one meter that fulfills all my metering needs. Some meters have special Zone System modes that greatly simplify the implementation of the Zone System and for at least one, the Pentax Digital Spot Meter, you can purchase a Zone System scale that gives you a visual representation of the zones and their relationship to one another.

Whether you are shooting with a digital camera or still prefer film, a spot meter can give you the edge in controlling exposure, help you to achieve more mastery of your medium, and improve your technique, allowing you to create more expressive photographs. A worthwhile investment, don't you think?