All Photos:
ISO 400
F-stop f/3.4
Varying Exposures
These two photos show the differences between Perou and Leibovitz's styles. For a start, there are clear differences between key features. For a start, the lighting has clear differences. Leibovitz uses a soft, natural light for a lot of her photos including this one to avoid dark, contrasting shadows that draw away from the subject, as this lighting gives a smooth, elegant shadow that doesn't dominate the photo. But Perou who appears to favour bold, black shadows that often are one of the main parts of his photos. 
