Tuesday, January 5, 2016
Light Meters Handheld vs. In-Camera
In our last blog entry, we talked about using the in-camera meter to make a proper exposure. Let’s explore that a little further and also talk about the advantages of the hand held meter.
There are basically two types of light meter; reflective meters and incident meters. The meters in our cameras are of the reflective type. That means that they measure the amount of light that is reflected from the surface of the subject to determine an exposure that will render the scene as a middle gray.
A caveat in that is that different colors reflect different amounts of light. If the scene is mostly dark colors, the meter will try to compensate for the darkness and increase the exposure. If the scene is mostly light colors, the opposite would be true with the meter suggesting a value that would decrease the exposure.
Remember that the in camera meter usually defaults to evaluative metering setting so that it averages the whole scene to reach that middle gray value. We can “fool” the meter a bit by changing the metering mode to either center weighted (partial) metering or spot metering.
Center weighted or partial metering will look at a smaller area in the center of the frame and ignore the rest of the values outside that area when making the choice of proper exposure. The same is true with spot metering, but on a much narrower field of view. In the case of partial or spot metering, we would simply center the main subject, push the shutter release halfway down and hold it while we recompose the image for a better composition. Then we have to make an educated guess to bring our subject to the correct exposure, unless, of course, our subject is middle gray.
As an example, let’s say the in camera meter, set at the factory default of evaluative metering, tells us that f/8 is the proper exposure but our field of view is primarily dark. We would have to close the shutter down one or two stops to f/11 or f/16 to darken the image to make the blacks black and the whites not blown out. In contrast, in a light scene, we would have to open up the shutter from f/8 to either f/5.6 or f/4 to get the proper exposure.
Hand held meters are generally incident meters, meaning that they measure the light falling ON the subject rather than the reflected light. Because of that, the measurement is not subjective to the different colors or tones in the scene and will give us a more accurate exposure calculation. Place the meter near the subject pointing toward the light source. That will give you a very accurate exposure for the lighted side of the subject. If you have multiple light sources, you can measure them separately and determine your settings based on the effect you wish to achieve. Click here to see some really great handeld meters by Sekonic.
Most hand held meters will also act as a flash meter for strobes or studio flash. Putting together complex lighting ratios becomes a much easier task using a flash meter and eliminates a lot of the test shots and guess work.
Which type of meter do I use? Both! Each has it’s place, but when I am being a lot more critical with an image, I will always defer to the hand held meter. The accuracy of exposure is always more precise.
If you have any questions, please leave a comment or send me an email (jmhillphoto@gmail,com). I will do my best to answer all.
Keep shooting! The more you shoot, the more you will see!