When lighitng a human face the height of the key light is dicated by duplicating the downward modeling of natural light and keeping it flattering by getting it past the brow and into the eye sockets. Anything lower that 30 degrees begins to look unnaturally low and flat (unless trying to mimic late afternoon when sun is low) and anything higher will usually cause the brow to shade the orbits on humans. YMMV on ceramic trolls and young kids who don\'t have fully developed faces.
The expression clues in a portrait come from the mouth and eye area. The nose by comparison could be considered a distraction from those desired focal points. It can be more or less of a distraction depending on how it is lit.
When key light is centered on the nose (and raised 45 degees above the eye-line) both sides of the nose are highlighted and blend into the similarly lit cheeks and perceptually the nose \"disappears\"; the view isn\'t likely to notice it consciously (Wow, look at that nose!) or have it become a sub-conscious distraction from the eyes and mouth.
You may have seen the new painting of Princess Kate that\'s causing a buzz because it\'s not very flattering. One reason it there\'s a very dark shadow hanging along the side of the nose. Had she been depicted with centered light there wouldn\'t be that distraction.
Moving the key light off center causes the nose shadow to fall sideways. On a human nose when the light gets 45 to the side and 45 above it\'s shadow will fall down along the base of the side with the shadow from the tip often falling exactly over the top of the nostril on the shaded side. That combination is desirable because the brain gets the clues about the 3D size and shape of the nose from the size and shape of the shadow it casts. When the shadow covers 1/2 the nose it accurately models the nose.
Modeling the nose accurately can be a good or bad thing when trying to flatter the subject depending on the nose. A strategy for deailing with a huge nose is to aim it straight at the camera (full face view) and center the key light so it doesn\'t cast a sideways shadow. The shadow is cast down, and if the camera is raised to look down slightly on the top of the nostrils (not up them) the shadow will often be hidden by the nose.
In a full face view a key light to the side creates an asymmetrical pattern. If you were to compare a naturally symmetrical face with centered and side lighting from 45 degrees. You\'ll see by comparison the highlighted side nearer the key light will seem larger than the shaded side. It\'s one of the many optical illusions that fool our brains you should be aware of when lighting a face if the goal is to make it appear symmetrical and slim.
The optical illusion that makes the highlighted face seem bigger in a full face / side lit view is used to advantage in an oblique facial view. Turn the face 45 to the camera but keep the light 45/45 from the nose/eyes behind the subject (90 degrees from camera axis) and the key light will create a \"mask\" of highlights which the brain will focus on, perceiving the face as being symmetrical and slender, even if it is neither in a full face view. So when you encounter an average human with a face that is lopsided to some degree the oblique angle w. 45/45 key light position one you should try.
The Gnome is not a good subject for learning to light human faces, nor are mannikins, because they usually are endowed by their creator with perfectly symmetrical features.
With humans starting with a full face pose and centered lighting will show you whether or not the face is naturally symmetrical by how the lighting pattern falls. If the net result doesn\'t look symmetrical it indicates the face is lopsided. If try putting the key light on the narrower side at 45/45 in a full face view (which will create the illusion of better balance), and at 45/45 with the oblique and see if the combination of facial angle + key light angle make the face look more symmetrical. Then try every other combination and compare results. These aren\'t rules, just conventions based on observation of what combinations are more flattering.
The other variable to discuss is the fill, which controls the tone of the shadows. As mentioned the centered strategy is used in a full face pose to make the nose not be noticed by eliminating the shadow on the side. When you do opt for a lighting with key light to the side and it casts a visible shadow what controls how distracting the shadow will be from eyes and mouth (i.e. making and holding eye contact) it how light or dark it is in the core umbra shadows. The lighter the shadows are the less distracting they are and the better surface blemishes which cast shadows are hidden.
Fill controls the tone of the shadows. Ideally it should come from the front of the subject because place to the side and further back than the tip of the nose the subject\'s hair and shadow side cheek can shade the fill. If you look critically at your test shot you\'ll see small areas of very dark shadows in some low spots on the face. Those are the areas where the key light is casting a shadow and some other part of the face (e.g. the cheekbone) shaded the fill.
It\'s logistically difficult to get a reflector where it will be out in front of the face so it can bounce fill into the smile lines, mouth and base of the nostrils, keep it out of camera view, and where it can catch and reflect the key light. Most position it where it can catch the light and is out of view and it winds up too far back and to the side creating shaded fill those areas.
All things considered it\'s easier to use a second light for fill, centered and placed about chin level with the subject. From there is creates flat nearly shadowless light on the face, but if you think about it you should realize that\'s a good thing for fill. If your fill source is casting shadows anywhere you see it\'s shadow there will be an unfilled void on the subject (if you don\'t have \"spill fill\" from your lights bouncing everywhere off the walls and ceiling.
Again I stress there are no rules, just cause and effect so try what I suggest, observe the results from the criteria of whether it makes the face look symmetrical and flattering (no distracting shadows) then try everything else and compare; with one light + reflector and with separate fill and key lights if you have them.
Jan 13, 2013 at 05:15 PM
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