My brother has worn glasses full time for absolutely years, which has meant that I learned how to photograph him wearing them to avoid hideous green glare rather intuitively. I probably did have to think about it at some point, but I don't really remember and now I just seem to do it. That was until this week, when one of the students at Photocritic Photography School piped up and asked me what he should do when he has a portrait subject who wears glasses. For lots of reasons, the answer is never 'Ask your subject to remove them,' so what do you do?
Look at the light
The most obvious problem that glasses will present to you is that they reflect light. Instead of seeing straight through spectacles' lenses and into your subject's eyes, you'll have a unpleasant, usually green-tinged, reflection glaring back at you.
Going back to GCSE physics, we know that the angle of incidence (or the angle at which light will hit someone's glasses) is equal to the angle of reflection (or the angle at which the light will bounce back off the glasses). If light is coming in at an angle of 31° to the normal of your subject's glasses, it'll bounce off at 31° on the other side of the normal*. There's a helpful diagram here.
Consequently, if your light source is too close to your camera the light has a much greater chance of bouncing straight off your subject's spectacles and into your camera's lens. And if the light is coming from straight behind the camera and your subject is looking straight back at the camera, you haven't got a cat's chance in hell. But the upshot is: know where your light is coming from.
* The normal is an imaginary line running perpendicular to the plane of the glasses.
Altering angles
Minimising glare is easiest by one of three means:
- move your light source
- move your subject
- or move your camera
By shifting your light source or yourself, you can alter either the angle of incidence, and therefore reflection, or take your camera out of the firing line. Sometimes, though, your light source can't be shifted (say, when it's the sun) and you moving might not be an option. Then it's down to your subject.
Tilting and turning
If your subject tilts her or his head downwards, just by a few degrees, not by much, it'll be sufficient to adjust the angle of the light and prevent a reflection bouncing back into the camera lens. Or she or he could turn fractionally away from the light source; not enough to wreak havoc with your shadows, but enough to prevent that horrible glare.
When you ask subjects to tilt their heads or change the angle of their shoulders, you might find that their spectacle frames begin to encroach into the view of eye. At this point it becomes a trade-off between reflection obfuscation and frame obfuscation. You need to decide where your tipping point is.
Quit posing
If you opt for more candid shots, you'll be able to capture your subjects looking away or looking down and doing it naturally but still without any nasty reflections.
Go with it
Sometimes, you just have say that the glare is there and it's better to have a photo with a reflection than no photo at all!