usually have dark shadows in the eye sockets due to the steep downward angle of the sun and the preference of the subjects not to be blinded by the sun. When near-axis fill flash is added in that situation it hits the shaded eyes and sunlit face equally so the eyes will always remain darker than the face. What happens on a cause and effect level is the flash acts like fill and more key light where it overlaps. The eyes will seem brighter due to the addition of catchlight reflections from the flash but they will still look dull and lifeless. So while near axis fill works in the technical sense and works fine for general candid shooting it isn't the ideal strategy for a close-up portrait were the eyes are a more critical focal point. The more ideal strategy for portraits is open shade or backlit which allows the subject to raise their face and eyes into the skylight without squinting. Flash could make the shadows darker In sunny backlight the problem is more contrast than the camera can handle. But on an overcast day the problem is a lack of contrast. In overcast conditions adding flash will have the net effect of making the shadows darker. Even if the flash is near-axis fill flash it will fall off front-to-back more rapidly than the natural lighting and increase contrast. If moved off axis the flash becomes a "key" light and can be used to create a higher contrast directional lighting pattern on the face. The greater the amount of off-axis flash added, the darker the shadows will become after exposure is adjusted for normal looking highlights. See also Fill light Photographic techniques External links