The Image here is of my daughter Claire. This image I titled "Naked Booty Time". I love the image not just because she is my daughter but because it shows her personality. I know it is crazy to think that at this age they have a personality but it is true!
How it was done: High key is a very common style of lighting. Not only is the lighting style used, but it is also probably one of the most mis-used styles. Many photographers tend to put as much light on the background as they can just to make sure it is white. This is not needed. I highly suggest an external, hand-held light meter. In this case you will need a flash meter. A flash meter will read the power output of the studio flash and tell you what the f/stop needs to be to make an accurate exposure. With this meter you will set your ISO, and shutter speed. Based on these, the meter will calculate the f/stop. My style of high key lighting requires multiple umbrellas. I use two umbrellas on the background generally set to f/11. I will use my flash meter and measure multiple points across the background and will adjust the power and umbrella position until I achieve an even exposure across the entire background. This is important so the look is even and does not appear lighter or darker in spots in the final image. Next, I will place a 60inch octobox on the upper right side of the camera. The light will be feathered across the subject to only light them with the back edge of the box. This light will be metered on the highlight side of the face to the same power and exposure as the background. This makes the exposure very even. I then add a large reflector to the shadow side to soften them and lighten the shadows. The reason that I use an octobox instead of a rectangular soft box is that the specular highlight in the eye matches the shape of the eye. I keep the box to upper right side is to get the directionality of the light while getting detail in the eyes and keeping the specular highlight out of the subjects pupil. This is a great style of high key lighting!