With the summer holidays ahead I felt summery beach #photo was needed! Sarah was lit from the sun with a 580EXII flash used to fill in the shadows - especially important given the hat.
I wanted to ensure that Sarah was isolated from the background, but at the same time there was enough depth of field to get her completely in focus. From experience I guessed that f/4 was going to be about right @ 100mm. (I'd have gone f/2.8 for full body, and f/5.6 for a headshot).
One other point - never cut off a model's body in a photo at a joint - in the original shot I cut Sarah off dead-on the knees and it looked awful. I cropped in a little more and it was much improved.
Taken on the amazing Canon 70-200 f/2.8 MKII.
Canon EOS-1Ds Mark II, f/4 @ 100 mm, 1/1250, ISO 100, Flash