Because incident metering reads the intensity of light falling on the subject, it provides readings that will create accurate and consistent rendition of the subject’s tonality, color and contrasts regardless of reflectance, background color or brightness or subject textures. Subjects that appear lighter than middle gray to your eye will appear lighter in the finished image. Subjects that are darker than middle gray will appear darker. Colors will be rendered accurately and highlight and shadow areas will fall naturally into place. Neat trick, eh?

		White Plate
		Gray Plate
		Black Plate

Because reflected metering reads the intensity of light reflecting off of the subject, they are easily fooled by variances in tonality, color, contrast, background brightness, surface textures and shape. What you see is often not at all what you get. Reflected meters do a good job of reading the amount of light bouncing off of a subject — the trouble is they don’t take into account any other factors in the scene. They are merciless in recording all things as a medium tone.
Reflected measurements of any single tone area, for instance, will result in a neutral gray rendition of that object. Subjects (like a white cat) that appear lighter than gray will reflect excess light and cause them to record darker than they appear. Subjects (like a black cat) that are darker than gray will reflect less light and result in an exposure that renders it lighter — in other words, a gray cat instead of a black one.

White Plate
Gray Plate
Black Plate