cgardner wrote:
The first thing to realize is that the flash is the frontal KEY light, not the fill. For example in the photo below, taken with a flash + small diffuser on a bracket, it is the flash which is creating the "mask" highlight pattern on the face..
The fill light in that backlight scenario comes from the sky the person is facing, which is usually 3 stop below the sunny side. What the raised flash does is overlap that fill and create the highlight pattern over it. Note the highlights on the tops of the cheeks and chin which create the mask pattern our brains recognize as "normal" because faces are usually illuminated from above as I did with the flash. That is why getting the flash above your subjects on a bracket by 12-18" is a critical element in making flash lit faces look normal and real instead of flat-lit like a deer in the headlights.
So in terms of exposure, you'd expose for the highlights in the white dress and face, keeping them about 1/3 stop below clipping. A situation like that doesn't fit the metering algorithms, and will "fool" the metering. I make my exposure decisions based on the over-exposure warning in the highlights, keep both the ambient background and the flash lit highlights below clipping.
Once you grasp the front flash is "key" light in a backlit situation you should see that lighting a face with flash outdoors is actually identical in terms of goals and flash strategies:
Full face pose: Raised-centered key light (i.e. butterfly pattern)
Oblique pose: Key light light placed 45 degrees from nose on far side (i.e. short lighting)
The only difference outdoors (with the sun at the back as hair light) is that the wrap around fill of the sky assists both the key and fill flashes. As with indoor shooting you will get more flattering results by using two flashes outdoors in an overlapping key over even fill pattern.
As noted above the sky fill is 3 stops below the sunny side. If the "key" flash lifts the highlights on the shaded side of ambient on the bride's dress and face to just below the highlights creating on the edges by by the sun, the non-flash lit parts in front (i.e. the shadows filled by the sky alone) will still be middle gray, 3 stops darker. Some detail in dark areas may be lost.
For more complete control of the frontal lighting on the faces and clothing use two flashes:
When using two flashes outdoors in a centered "butterfly" pattern I put the second off camera flash below the camera like this:
The flash on the bracket acts as Key light creating the highlights, just as with the single flash example above with the slave acting as fill to augment the sky fill. In that configuration the shadows in front get [ sky fill + slave flash fill ] and the highlights get [sky fill + flash fill + master key flash ] as in any key / fill flash situation the key light overlaps the fill to create the ratio. The only difference outdoors vs indoors is that the ambient sky lifts both.
For a short lit oblique pose the role of the flashes changes. The slave moves behind the subject 45 degrees from the nose where it will highlight only the front of the face, leaving the broad side in shadow. If only the sky light was used as fill the shadows on the side of the face would look dark and harsh. To prevent that the Master flash on the bracket is used to augment the sky fill as the foundation for the lighting ratio: the shadows in front get [ sky fill + masster flash fill ] and the highlights get [sky fill + flash fill + slave key flash ].
If you try those dual flash scenarios with direct flash you will be amazed how soft the transitions on the face are. That is the result of God's own soft box - the wrap around fill of the sky, being the foundation for the lighting. The flashes in those configurations don't fight the direct sun in front, they simply augment the soft light from the sky.
Compared to the sky even a 60" umbrella is puny and will not have much effect on the shadows. But where you will notice the difference with diffuser size is in the catchlights of the eyes and hot spots on damp or oily skin. Larger modifiers will create larger more attractive catchlights and less specularity in the skin highlights. As with any lighting scenario how big of a diffuser to use is a balance of logistics and results. If you experiment starting with direct flash, noting the highlights and gradually add larger ones you will likely find you can achieve a good balance of convenience and results with modifiers which are smaller than those typically used indoors where there is no key fill to assist. Also if you use the neutral-fill dual flash configurations I suggest you will find the fill light lightens and 'softens' the shadows and its not necessary to use a huge wrapping key light modifier. Less is more on a windy day outdoors
One final note when shooting outdoors: BRING A LADDER
When a person is facing the sun high in the sky the brow shades the eye sockets and they fall below the range the camera can record. The same thing happens with the sky light when the subject is posed facing the sky. The light from the sky will be shaded by the brow, resulting in eyes which are darker than the cheeks. No matter how much flash you add the eyes will always be darker than the cheeks. The solution to the problem is raising the faces of the subjects up into the light so it reaches the eye sockets. Then the camera position needs to be raised by the same amount to keep the lens above the eye line so the nostrils are hidden from view.
Can you explain what "For a short lit oblique pose the role of the flashes changes" means. What can you tell me about shooting in the shade (under a tree)? Butterfly worth it or just on camera flash?
Zenon Char wrote:
Can you explain what "For a short lit oblique pose the role of the flashes changes" means. What can you tell me about shooting in the shade (under a tree)? Butterfly worth it or just on camera flash?
I don't know if you wanted only Chuck's response, but if I may add my two cents' worth...
If we start by breaking down the terms:
An oblique pose means the subject isn't looking straight at the camera. If you picture the nose dividing the face into two halves, when the person is looking straight at the camera, the two halves are of equal width. If the person turns partially to one side or the other, the halves will no longer be equal; one side will be broader, and one side will be narrower ("shorter").
If you bring the key light around beside the subject, so that it is lighting the "short" side, the broad side will be mostly in shadow. This is called short lighting, and is a dramatic way to light a face. It also creates a slimming perceptual effect that best suits some subjects. If the key light is raised so the it creates a loop pattern, and at the same time the subject is facing obliquely, you get a combination pattern called short loop.
In order to create a short light outdoors, you can't use a flash over the camera as the key; the key light must come from an angle. So if you have only one flash, it must be used off camera. If you have two lights, the on-camera flash can be used to supplement the skylight as fill, and the off-camera light can be the key. (The "on-camera" flash could also be raised on a bracket, used on a light stand near the camera, etc. The important point is that the light hitting the subject from the short side must be the dominant source for it to be "short lighting.")
Shooting in the shade can help reduce the dynamic range of the overall scene so that the highlights and shadows both fit within the range that your camera can capture. And since the subject won't be in direct sunlight, it will be the larger skylight lighting the subject, which can help to soften the fill.
You can create any lighting effect outdoors that you can indoors, with enough practice and the right equipment. Short lighting, butterfly lighting, whatever...it's up to you. Experiment, and find what works best for you and looks best to you. It's art, after all.
Zenon Char wrote:
Can you explain what "For a short lit oblique pose the role of the flashes changes" means.
In simple terms you want to create a "mask" highlight pattern on the face with the flash which makes the face look symmetrical from the point of view of the camera:
When the face is full to the camera a centered key light strategy will result in a symmetrical "mask" pattern. When the key light is moved off axis with a full face view one side of the face is highlighted more than the other. Its a common practice, but one which on careful analysis can be seen to make the face look unbalanced because the brighter side will look bigger perceptually. That optical illusion can make a perfect face seem a bit lopsided or if used skillfully make a lopsided face seem perfect.
The advantage of the oblique view, where the camera is 45° from the center line of the nose, is that in reveals the shape of the cheekbones, nose and other facial geometry in ways full and profile can't. In terms of basic goals, we still want the viewer attracted to only the front mask area of the face, but to find it they need to get past the nearer side if the face.
To create a mask pattern for 45° view of the face the a different key light strategy is needed. This is easiest to grasp of you put away the flash, grab a willing victim and find a window on the north side of your house (in the US) where the light is indirect.
Put the person a few feet away from the window at about and adjust their position relative to the light until only the side of the face towards the window and the front of the face is highlighted with light in both eyes and cheekbones, but the side of the face in shadow. Watch the outer edge of the near eye and keep the highlight pattern between the eyes, not wrapping past the eye and hitting the near side ear or side of the face. You will find they wind up facing the window at a 45° angle.
Once you get the light on the face set, walk around the face as shown below:
Starting near the wall you should see the 45° key light pattern from a full face 0° point-of-view. The highlights will create a mask, but it will not be symmetrical: e side nearer the window will look larger than the shaded side.
Walk around to 45° from the center of the nose. From that POV, 90° from the key light, you should see the mask pattern on face and it will look symmetrical. Its the optical illusion which makes that combination of 45° lighting angle and 45° camera vantage point so flattering: the face looks symmetrical and slim.
Keep walking around until you are 90° from the nose, looking at the face in profile. From that POV the key light is an an angle of 135°. If you've aligned the face to the light well you should see something like this:
Remember the goal of attracting the viewer to the face? Here the focal points are the eye and the mouth. What sets up the eye as a focal point is keeping the side of the nose in shadow. If the face were to move towards the light a bit more and light the side of the nose it would become a distraction which trumps the eye. A profile view when it splits the face exactly in half and is lit like above, creates another optical illusion which tricks the brain into thinking the other side of the face looks exactly the same. Its not a pose you may use often, but can be the most flattering way to photograph someone with a very asymmetrical face.
What this window exercise shows is that all three views have the the same key light position relative to the face 45° and changing camera POV make the face look most slim and symmetrical at viewed from 45°. The full face view lit from 45° isn't as symmetrical as when the key light is centered in light with the nose, but that can be modulated by making the shadows lighter or darker with the fill source near the camera. You might not often use a profile view, but its a way to check visually how the nose is being modeled by the shadow.
If you do the window exercise you should better grasp where a flash need to be in relation to the face to create the mask pattern in an oblique view.
The light is now 45° to the right of her nose. The light is still flattering with no distracting shadow from the nose because the angle of the light from the bracket hides the nose shadow behind and downward where its not seen by the camera. That's part of the rationale for the bracket - it manages to hide most of the distracting shadows.
If we were to add an off camera flash to that shot, it would need to be placed 45° to the left of her nose, 90° to the left of the camera axis, to create a highlight "mask" on the front of the face.
Zenon Char wrote:
What can you tell me about shooting in the shade (under a tree)?
My advice don't shoot under trees with flash. The light filtering through the trees turns it green. When you add the flash it creates a mixed lighting situation. Outdoors keeping your subject away from anything that will create reflected color casts result in more natural looking skintones.
Zenon Char wrote:
Butterfly worth it or just on camera flash?
Put the flash on a bracket 12 -18" above the lens of the camera at the pattern it creates is butterfly. The flash is creating highlights (becomes the "key" light on the face) and if its too low the angle of the light and the lack of 3D modeling will make the flash look fake.
