Catchlight, by definition, is a light source that causes a specular highlight in a subject's eye in an image. They are also referred to as eye lights or Obies, the latter a reference to Merle Oberon, who was frequently lit using this technique. A catchlight may be an artifact of the lighting method or have been purposely engineered to add a glint of "spark" to a subject's eye during photography. This technique is useful in both still and motion picture photography. Adding a catchlight can help draw attention to the subject's eyes, which may otherwise get lost among other elements in the scene.
A catch light is not the same as the red-eye effect; in general, red-eye is an undesired effect (caused by the reflection of light from the retina inside the back of the eyeball), while catchlights are often aesthetically desirable, and produced by light reflecting from the cornea. Especially in portraiture, eyes without catchlights are often said to appear dull or lifeless. Lighting is often arranged in-studio portraits specifically to create attractive catchlights.
As a specific light source, a catch light is usually fairly dim or focused, as to not affect any other part of the scene or face. Many other lighting methods, however, are known for the distinctive or unique catch light they produce. Among those methods are ring lights, which produce several highlights in a ring, and large softboxes, which produce large, square highlights. While catchlights most often appear to be simply bright spots, as reflections of the surroundings they can contain entire images.
When I was a young child, I thought we all had catchlights, all the time. I learned catchlights were something added by sunlight or artificial light, by the time I was in junior high. I loved pouring over magazines and was fascinated with catchlights and how to achieve them.
Do you remember the first time you noticed a catchlight, in someone's eye?
Let's go over how to create a catchlight.
First, you should:
Find your light source.
In any photo shoot…whether professional, hobbyist,
Where is your light coming from? Look around.
Are you outside? Are you in the open shade? Are you inside? Where is your light coming from?
Open Shade:
Light source: sun, filtered by the shade of the walkway.
Open Sky:
Light source: sun, filtered by the distance of the sun in the evening light.
Window or door:
Light source: Photo taken inside, facing the window.
Electronic:
Flash: Taken in a photo studio, indoor, or outdoor space.
Light source: electronic or continuance artificial lights
If photography is without artificial lights, turn your subject to face your light source. Look into their eyes to see where the catch light is reflecting in your subject’s eyes. Move or tilt the subject's face or body to where you feel the catchlights have the look you want.
With an artificial light source, how high and how far to the right or left will affect the catchlights in the eyes of your subject. I find that having the light source at a 45-degree angle, pointing down towards the forehead of the subject creates a nice catchlight. It takes practice and talking to your subject as to where the catchlight should and will fall.
Be careful with any light source that is going directly into someone's eye. Some people are very sensitive to light, while others may not have a problem. Ask your subject, before any photography if there is an issue that you would have to be made aware of.
In post-production, you can create your catchlight. Many photographers feel the catchlight has to be in a certain position in the pupil. I do not agree with that train of thought. You can experiment and find what you like best. Some photographers do not clean up their catchlights in postproduction. Again, I feel this is a personal choice. Try different techniques to create the look you feel, works best for you.