When you set your camera to Portrait mode, it automatically chooses a wide aperture (like ƒ/2 or ƒ/2.8) to create a shallow depth of field. This helps to isolate your subject, visually separating him or her from the background. The closer you get to your subject, the more noticeable the effect will be, so stand just a few feet from your subject and fill the frame with his or her head and shoulders.
To strengthen the effect, set your lens to a longer telephoto setting and keep an eye on the background, choosing something simple as a backdrop to minimize distractions. Some cameras also utilize face-detection focusing in Portrait mode, and enable red-eye-reducing fill-flash and a subtle softening effect for pleasing skin tones.
Sports mode is built for capturing fast action. To that end, the camera will select its fastest available shutter speed and may increase the ISO to accomplish this. The aperture is likely to open up and create a shallower depth of field, which could become an issue with a fast-moving subject.
Because of the high shutter speed, the camera won’t use a flash, and if it has the capability, it will utilize continuous focus-tracking and high-speed shooting so you can fire off several frames in a row.
The best way to photograph a fast-moving subject (like a runner or a cyclist) is to pan the camera with the motion as the subject crosses the frame. If you’d like to minimize the speed of that movement, position yourself so the action is moving toward the camera or away from it, rather than laterally across the scene.
Use Macro mode for shooting small subjects (like insects and flowers) or for close-up details. On some point-and-shoot cameras with motorized zooms, this mode will spur the camera to automatically choose the focal length at which it can focus closest.