We had a model in the studio today and photographed her as a dental hygienist seen from the perspective of the patient. Later this image was composited with the photo from the blog post of a few days ago. Because I shot each image specifically to be composited I was able to prepare them in a way that made the job of putting them together easier. The hygienist, for instance, was photographed back lit by a studio tungsten lamp placed behind her to simulate the same type of lighting from the dental light. Also I photographed her from the same position I was in when I took the background shot, and used a similar lens focal length and depth of field. As a result of this preparation, the two images blended together naturally, and the whole composite took only 20 minutes to complete.