Position of Flash Unit Mounted to Wimberley Head
Many customers ask about the position of their flash unit. We have compiled some information to help address some of these concerns.
Question: The Wimberley Head Flash Bracket seems off-set. Do I need to position my flash unit directly over the lens barrel, or optical axis?
Answer: In speaking with Clay Wimberley, company president and chief product design engineer, about this at length, Clay stated that this offset was a compromise in the design of the flash bracket system. The F-1 and the F-6 Telephoto brackets position the flash over the center axis of the lens barrel. The Wimberley Head bracket (old F-4 and new F-9) are about 3/8” off-set due to being mounted on the swing arm of the Head. Clay wanted to avoid making a special, further-reaching Tilt Arm module just for use with the Wimberley Head to keep the bracket system from getting too complex.
The 3/8” off-set is not noticeable in shots with long telephoto lenses, especially if you are using a flash extender, such as the Better Beamer. It may be more noticeable if the flash arm is tilted unintentionally or when a subject is closer to the camera. Clay suggested making sure that the screw in the swivel joint of the Wimberley Head flash bracket module is tightened enough so that it does not creep or tilt. He also stated that he cannot imagine that this 3/8” offset will affect the ability of the user to successfully add sufficient fill-flash on the subject. We have not had any professional wildlife-photographers state that this off-set is an issue with their photography; otherwise it would have been corrected many years ago.
Does the offset really matter? Yes and no. It depends on where the shadows from the flash will fall. If the flash is mounted directly above the lens and aimed directly at the subject then the shadows are typically behind the objects. When the flash is moved left or right of the lens, or the light from the flash comes at an angle from the lens, the shadows will be towards one side of the subject. An offset of 3/8”, is not enough to create much of an issue.
When photographing wildlife, how can I reduce eye shine or “steel eye”?
The redeye effect.
Redeye occurs when the light from the flash unit bounces off the blood vessels lining the retina of a person and animal’s eye. The result is the familiar glowing red eye effect. When light levels are low the pupil of the eye will dilate letting in more light. If you take a photo of a person with flash their irises don’t have enough time to react to the light, so their pupils will remain dilated. The problem doesn’t occur very often in daylight partly because the pupil of the eye contracts and reflects less light.
The problem of redeye is more pronounced the further you are from your subject and so becomes very apparent when shooting portraits using telephoto lenses. This is because it’s an issue of how narrow the angle between the subject-flash and subject-lens distances is. The smaller this angle - whether because you’re a long way away from the subject or because the flash is too close to the lens or both - the greater the chance of redeye.
The flash photography of many animals can involve an increase, but slightly different, problem. Many animals have a reflective membrane in their eyes called the tapetum lucidum, a layer of tissue, lying immediately behind the retina in the eye which helps their night vision. The tapetum reflects light from a flash unit more efficiently, and tends to color it green or blue. The membrane also explains why the eyes of animals are clearly visible as brilliant points of light when light is shown. Humans do not have the tapetal layer.
Redeye reduction in Wildlife Photography
There are a number of ways of dealing with redeye or steel-eye in wildlife photography. The first, and generally most effective, way is to raise the flash higher above the lens, by mounting it to a flash bracket, thereby ensuring the light from the flash hits the eye at an oblique angle.
If direct flash must be used, a good rule of thumb is to separate the flash from the lens by 1/20 of the distance of the camera to the subject. For example, if the subject is 2 meters (6 feet) away, the flash head should be at least 10 cm (4 inches) away from the lens. You can use our Module 6 Extension Post to increase height on the Wimberley Flash Bracket.
Posted on September 17, 2015 at 6:24 pm