Measuring Light with Photographic Light Meters - dummies

Measuring Light with Photographic Light Meters

Part of Digital Photography Lighting For Dummies Cheat Sheet

Photography is all about light. How you measure that light for your digital photos, using various light meters, brings different results to the digital images you capture.

The first step in figuring out what settings to use to take a photo is to measure the light. An accurate light measurement makes choosing exposure settings on your digital camera much easier.

Two methods used to measure light are employed by the following types of light meters:

  • Incident meters measure the amount of light falling on a subject and work best when held in front of the subject and aimed at the light source.

  • Reflected meters measure the light that is being reflected off a subject and work best when you aim them at the subject. The built-in meter in your camera is a reflected meter. Reflective meters believe that the light they’re reading is an average 18 percent gray and can be more easily fooled by scenes with a lot of light or dark areas.

Here are your options for photographic light meters:

  • Handheld light meters come in both incident and reflected varieties with some making both available on the same meter.

  • A built-in light meter comes built into your camera and works the same way as the handheld reflective light meter — by measuring the brightness of the light in your scene. Most built-in light meters have three modes:

    • Matrix metering breaks the whole scene into pieces and then takes the meter readings from those segments to build up a more accurate reading of the overall scene. Matrix metering works very well in most scenes and is the mode you’re likely to use most of the time.

    • Center-weighted metering places more value on the light in the middle of your scene than the light on the edges but still measures the light from the entire scene. This metering mode was originally used mainly for portrait photography, where the subject fills most of the frame and the background isn’t as important. It’s a good choice in any case where your main subject fills most of the frame and is close to 18-percent gray.

    • Spot metering limits the light reading to a tiny area in the frame and ignores everything around it. Spot metering is very useful when you have a critical area in your image that you want to make sure gets the right exposure and is close to 18-percent gray.