In photography, and in its most layman-understandable terms, contrast is the (1) difference between light and dark; (2) variation in texture or (3) variations in tones or colors. The difference between light and dark, or lighting contrast, determines the mood of a photo. A low contrast may make a photo look subdued; a high contrast may make an image appear more dynamic.
Inside a studio where lighting can be staged, getting the right contrast is not so much of a problem; outdoors, it is totally a different issue because you are at nature’s mercy.
I have learned that one of the most useful techniques to learn about lighting contrast between subject and background is to stand directly under a tree in broad daylight, point the camera upward and shoot. It’s a kind of a reverse technique. We’re always told that the light should be in front of the subject to take a good photo. But when you’re standing under a tree, it is the complete opposite — the light is always behind the tree.
Try to take photos from under different trees at different times of the day. Adjust your camera settings, use different aperture and shutter speed settings, to make the tree pop without turning the sky too bright in the background.
It’s a challenging experiment, I tell you. The sky is different from minute to minute, no two trees are ever alike and you will get different amounts of light filtering through the branches and leaves every time.