Flash creates irritating reflections on eyeglasses.
Flash can be difficult to work with. Especially pop-up flash.
In particular, reflections on eyeglasses make ugly highlights. On-camera flash is directly parallel to the optical path of the camera. The light from the flash travels right down the line, hits the glasses and reflects right back into the lens. This can cause ugly bright reflections, highlights in the eye space of the glasses. Picture ruined.
Get off the optical path
The use of flash should always be off the optical path if you want to avoid red-eye or reflections on eyeglasses. Ensure that you do one of two things. Use an off-camera flash where the flash is off-set to the side on a stand or convenient surface. Alternatively you can redirect the on-camera pop-up flash using a diffuser or some type of reflector. You can find out more about the latter in this post: “Does Pop-Up Flash Ruin Your Shots?”. Both these help to reduce the highlight problem. The light will be on the subject from bouncing off other surfaces. This reduces the direct effect of the light reducing the reflections on eyeglasses from direct rays.
Controlling reflections on eyeglasses
If you use off-camera flash, or any other type of light to illuminate your subject you can get highlights on the glasses. The key to overcoming highlights and reflections on eyeglasses is knowing the simple “Law of the angle of incidence”. The law states…
• The angle of reflection = the angle of incidence •
Basically, light hits a surface and reflects off again at the same angle. Simple!
The “Law of the angle of incidence” teaches us not to stand so your camera is on the same angle as the light reflecting off the glasses. This applies to any light, not just flash. Remember, that when you line up your camera you should look carefully at your subjects eyeglasses to see if there are any highlights you can avoid. If there are lights reflecting off the eyeglasses then move so the “Law of the angle of incidence” does not apply.
Remember to keep the catchlights
Of course the way that eyes look alive is that wonderful bright spot called a catchlight. As in the image above that feature of a reflection brings vitality to an image. To help preserve that, use a tiny bright point directly in the line of the optical path. If you have an off-camera flash you probably have a white pop-up card on it. You can use that card for making a catchlight. Point the flash beam to bounce off a nearby surface. When the card is up, it reflects a gentle light at the subject. At the same time the main beam of the flash is heading off for the ceiling or walls nearby. That little card on the flash reflects just the right amount of light directly to the eyes of the subject. The small size of the card is critical. It is not bright enough to cause bad reflections on eyeglasses. But it is enough to create that lovely bright spot. The eyes suddenly become alive. They are not blotted out with massive back-reflections.
Avoiding flash reflections on eyeglasses:
In the video Mark Wallace explains the Law with a simple diagram then sets up the ways you can avoid the highlights. Remember, his advice applies to any light, not just off-camera flash or studio lights.
Ep 214: Digital Photography 1 on 1
More about off-camera flash
Off-camera flash is a much more controllable way to light with flash than pop-up flash. If you would like to know more about off-camera flash, including how you can buy effective equipment at affordable prices see this post: Off-camera flash. It provides more information about the flash units and how to use them. There is Also advice on purchasing.
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