Flash: Flash on camera
A Speedlite is designed to be attached to the hot-shoe of the camera. This is very convenient, but it can produce problems.
When your subject is close to a wall, for example, direct light from the flash will throw a strong shadow onto the background. If the camera is being held horizontally (landscape format), the flash is above the lens and the shadow will probably be hidden from the camera by the subject. However, if you rotate the camera to a portrait format − very likely if you are shooting portraits − the flash will be to one side of the lens, and the camera will see the background shadow it creates.
You can avoid this problem by using the flash off the camera with the Off Camera Shoe Cord. This will enable you to hold the Speedlite above the camera, even when the camera is turned sideways. Using bounce flash is another option, as this will avoid direct illumination and also soften any shadows.
Flash on camera can be used for portraits if the camera is held horizontally , but if you turn the camera through 90 degrees to use a portrait format, the flash will throw a shadow to the left or right of the subject.

