Although you may hear the phrase "I'll fix it in Photoshop" come from the lips of a digital photographer, correcting mistakes is more time-consuming than getting it right in-camera. This is no truer when it comes to exposure, where poor metering results in the loss of crucial detail in shadows and highlights.
Today's cameras offer sophisticated meters with multi-pattern sensors and onboard processors that deliver excellent exposures for most shooting situations. Sometimes, even the best built-in meter falls short, however. In such challenging lighting conditions, a handheld spot meter provides the precision and control a photographer needs to achieve the best image possible.
A spot meter measures reflected light within a narrow angle of view of only one degree. Digital cameras often feature a spot meter, but the angle of view varies, depending on the focal length of the lens used. The fixed angle of view provided by a dedicated spot meter delivers a consistency that's crucial for achieving accurate results. By bringing the spot meter to your eye, you select the exact spot used to measure reflected light.
With today's digital devices, such as the Adorama Ambient 1° Digital Spot Meter and the Sekonic L-558R DualMaster, the exposure reading is displayed on the meter's LCD in the form of shutter speed and aperture, EV (exposure value) or luminance. You can measure shadows, midtones and highlights, and use this information to determine how best to expose for the scene.
For example, I was photographing a landscape at sunrise. With a built-in camera meter, the exposure would have attempted to retain detail in the surrounding shadows, but slightly overexpose the sky. By using a spot meter, I could meter off the brightest part of the scene, ensuring that I had written detail in the mist and sky.