The Power of Gray
Cameras are calibrated for exposure at the factory using what is known as a Gray 18 card, which is a shade of gray between light and medium gray. So, using a grey or neutral colored background helps your camera balance all the tones and expose the scene perfectly. This is especially true when the scene has a mixture of dark and light tones.
In the example below, the Smartweed plant, with its combination of red and white blossoms shot against a dark green meadow background, causes the camera to have difficulty balancing all the various tones and the white blossoms tend to overexpose.
If you adjust the camera's exposure value (EV) to properly expose the white blossoms, then the reds and greens become too dark. but when we shoot the same plant against a neutral background (in this instance a dirt road behind the flower), then you can see that the camera has no trouble rendering both the white and red blossoms very nicely.
So while you might think of gray as a bland, nondescript color, when used as a background for your subjects, it becomes a powerful tool to give you a perfectly balanced exposure. I use dirt roads and pavement as my neutral backgrounds. You can also use a Gray 18 card or grey cardboard.
Below are some of my favorite photos captured this way. Again, I used a Canon Powershot SX130 and the Little BigShot macro lens for all of these shots.
