"Kiss of Light" is a (Joe) McNally-ism. Simply stated, it's light that doesn't dominate the image, gently supports the existing light. It should not cast a shadow of its own.
This photo was a cull* from a series of photographs from the Obon festival I made here in San Mateo.These shots, made in open shade, weren't worth considering for publication. However, when discussing exposure problems with a former student who was also there, I used some of these images to illustrate some potential exposure problems. I liked this particular shot well enough to make it the subject of this brief post. Two of these shots were labeled to be simplify identification in an e-mail message.
Open Shade: Besides a bluish tint. This can normally be corrected by selecting the cameras Open Shade white balance preset. Open shade also tends to be flat lighting with no sharp-edged shadows.
Imagine, if you will, an environment where light is coming from the left and right sides, as well as from above. I was standing in front of a large building when I made this photo. This prevented any skylight from landing on the front of my subject's face. You can see that the cheeks and the forehead are lit, but the region below the chin, the eyes, and the teeth are not.
Front Light: This shot, also made at 1/1000 of a second, F 4.0, and at ISO 800, had a full blast from an shoe-mounted SB-900 speedlight. Just so that you know, the D7000 body was set to allow High Speed Flash Synchronization, so I wasn't limited to the normal ceiling of 1/250 of a second. The flash output was set manually because I couldn't rely on the camera's ability to properly render an image when the foreground subject occupied such a small percent of the total image area, as it did here. At full power, all existing facial shadows are essentially obliterated, and any sense of three- dimensionality removed from my subject's face.
Low Output Fill: The lead shot was made with the flash power turned to a much lower output level. A couple of things are happening here. First, the flash now serves as a "fill" light, putting light in the subject's eyes, teeth, and neck. Second, the flash, which normally produces the equivalent of a Daylight white balance preset, is warmer when compared to the camera's Open Shade setting. This warm wash of light, when added to the cooler ambient lighting, gives the subject a healthier glow. And third, the flash introduces "catchlights", or glare spots, on any reflective surfaces.
How Much Is Too Much? During this experiment, I dialed the power up and down, chimping all the while, until I got something that I liked. I did not record my settings, so I would have to repeat the process if the distance between my camera and my subjects changed significantly.
Fill Light: By definition, Fill Light brightens the shadows, but does not eliminate them. We can see the details in the neck, along with the proverbial sparkle in my subject's eyes. Notice that when using the flash fill close to the lens axis, the catchlight will always appear at the point closest to the camera.The catchlights might seem a little low in this photo, but if you think of the eye as the reflective sphere that it actually is, the position is exactly where you'd expect them. Then too, humans are "hard wired" to assume that light comes from above, like sunlight. These low catchlights just aren't right.
I can't explain why there's a catchlight on my subject's teeth. I suppose I could have cloned it out in Photoshop, but I didn't bother for these samples. I do hope that this illustrates how a small "kiss of light" can add a little sparkle to an otherwise flat, open shade image.
*There are a number of reasons why the lead image wasn't considered for submission. First, the composition doesn't include the drummer's left hand, and cuts off the tips of the drum sticks. The subject is positioned in front of a background that is much brighter than the foreground/subject, which tends to draw the viewer's eye away from the main subject. And last, the image really isn't that compelling.