At the very core of lighting theory are the three lighting tones that help us create the illusion of 3 dimensions on a 2-dimensional medium: the Diffused Highlight, the Specular Highlight and the Shadow.
There are a number of ways to show the illusion of depth in an image, such as perspective. Converging lines are powerful tools for artists to use, but what happens when you are shooting an organic subject such as a person. Perspective does play a role in a portrait – a person’s ears will appear smaller in relation to their nose, because they are further away. But we are so attuned to that relationship that it’s pretty much invisible to us.
A shallow depth of field can also help a photographer create the illusion of depth, but shallow DOF is not always the best answer as there are times when you want everything crisp. What does that leave us? Chiaroscuro – light and shadow.
Lighting is your most potent and stylistic means of showing the illusion of depth, and it can be used in infinitely subtle ways. Lighting is how we show shape and form, but it is also how we create mood and style and how we draw the viewer into an image. More specifically it is the contrast between the three lighting tones mentioned above that show the illusion of depth.
Here’s a quick description of the 3 lighting tones:
Diffused Highlights: These tones happen when light strikes a surface that is brighter than black. The light then reflects in every direction off of that surface, which means you can see a diffused highlight no matter what angle you view it from. For us photographers, this usually means areas of the image light by our key light (not always, but usually).
A neutral exposed diffused highlight will create tones that are true to what the eye see, or “properly” exposed tones. Reds will be reds, skin tones will look natural, etc. As a matter of fact, the only thing that affects a diffused highlight is how you expose it, and exposure is very much open to artistic interpretation. Sometimes you want to over-expose or under-expose a diffused highlight in order to create a particular mood, or feel to the lighting. You can learn more about diffused highlights here.
Specular Highlights: These are simply reflections of your light source off of the surface of your subject. How clear they are depends on how smooth and reflective the surface of your subject is. If you are shooting beautifully smooth, polished glass, then you will get a “mirrored” or perfect reflection of your light source. If your are shooting a surface that is less smooth, but still reflective – such as skin with oil on it – then you will get a less defined reflection of your light source.
We control the contrast of a specular highlight by manipulating its size – a larger specular highlight will appear dimmer. A smaller specular highlight will appear brighter. There are a few other considerations that affect specular highlights and you can read up on those in the tutorial on “Specular Contrast.” You can learn more about specular highlights here.
Shadows: This one’s pretty simple – a shadow will happen on a 3 dimensional object on the opposite side to which it is being lit. You can have “object shadows” such as the shadow side of the face. And you can have “cast shadows” (think shadow puppets on walls). Controlling the contrast of a shadow is a pretty simple affair – use either a fill card or a fill light. You can learn more about shadows here.
3 Dimensional Lighting
The vast majority of images have a combination of all 3 tones on their subjects. You can have an image that is almost all specular highlights, but it’s unusual (say shooting a piece of polished silver jewelry sitting on a mirror). You could have an image that was nothing but shadows, but that likely means you forgot to remove your lens cap.
It is extremely rare to have an image that is lit with nothing but diffused highlights. And I just happened to do exactly that with the image below.
In the shot above, I covered the model with non-reflective white make-up, which meant there would be no specular highlights on the shot. I also surrounded him with soft light from every direction to almost eliminate the shadows. I had to keep some shadows such as his nose, ears, eyes and lips, or you would be able to recognize him as a person. The result is pretty ethereal, and there is of course very little sense of form and shape. There are no contrasting lighting tones to create a sense of form, nor is there any shallow depth of field or major perspective. The only thing that gives the subject shape, is our brains filling in the blanks because we are familiar with the shape of the human face.
In the next image above, I removed the surrounding light, and lit the model from one side only. This creates shadow contrast and already the image looks much more natural to the eye. We can clearly see shape and form, although the model looks a bit like a sculpted bust rather than an actual person.
In the final image above, I had the make-up artist add reflective metallic make-up to the model, put clothes on him, and used a canvas background that I could let fall out of focus. Now the image has ample contrast between diffused highlights, shadows and specular highlights to show full form and also has a shallow depth of field to help accentuate depth.
Sometimes it feels like tutorials focus only on Photoshop – you do not have to use burning and dodging or “blend if” commands in Photoshop to show form. If you understand lighting theory, you can get it pretty much to perfection in-camera suing your lights. I recommend that you study lighting theory until it becomes second nature – it will absolutely make you a better photographer, and the lighting theory section on this website is completely free.
You can view how these 3 images were lit and produced here.
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Bluesky is a photography tutorial website created by veteran commercial photographer and college instructor Greg Blue. This site advocates an approach to learning studio & location photography that focuses first on light theory (these are free tutorials). Lighting, camera and post-production techniques are equally important, but should follow the study of lighting theory (these tutorials are also free). The site also offers a host of specific image tutorials that take a mile deep look at theory and technique from the perspective of individual images (these tutorials are members only).