Avoiding Common Mistakes with Flash. The ominous shadow competes for attention with the subject in this black and white picture. It could have been eliminated by aiming the flash so as to make the shadow fall into a position that is behind the subject or out of the black and white picture. It is difficult, particularly for beginners, to tell how the illumination cast by a flash will look until it's too late. The light's shadows and reflections are nonexistent until the black and white picture is actually snapped, and even then they disappear so quickly they are hard to catch with the eye. The black and white film catches them, though, sometimes with the results shown here. Shadows are a particular problem, especially in close-ups of people, because they are very noticeable when a single flash is aimed directly at the subject (rather than bounced off a reflecting surface). It is difficult to make shadows fall naturally unless the unit is removed from the camera and carefully aimed; this sometimes means that the flash must be mounted on a separate stand, or that one person must hold the flash while a second works the camera. Unexpected reflections of the flash itself frequently pop up from shiny surfaces: metal, windowpanes, a mirror (right), the polished surfaces of furniture or paneled walls. If the subject wears eyeglasses, these may be a problem; they should be tilted slightly. Flash illumination for color black and white film calls for special precautions against "redeye." This phenomenon is a reflection of the flash from the blood-rich retina inside the eye. It can be avoided if the subject looks away from the camera.