I was photographing equipment and soldiers on Fort Hood, Texas, when I came upon a crew working on the rotor blades of a CH-47 Chinook. Photographing people at work is one of my favorite subjects and, here, they illustrate why — details, action, focus.

There are other reasons the image is so striking — good lighting that doesn't overpower the subject, hands (often expressive, even if they aren't actually doing anything), and the eyes; always eyes. The mix of mechanical and human helps, as does the strong diagonal of the blade, but it's the focus in these soldiers' eyes that makes it work.

Here are other soldiers, this time inside a Black Hawk at the Libby Army Airfield on Fort Huachuca, Arizona. They are definitely focused on their job and I emphasized that by both focusing (no pun intended) on the soldier nearest me's eyes, and by putting a red gel over my off-camera flash. The truth is, these men would be looking at computer monitors displaying, essentially, natural colors. But for effect…

A2C2S BLACK HAWKSoldiers train with the A2C2S system in a Sikorsky EUH-60 BLACK HAWK helicopter at Fort Huachuca. Photo by Mark Bennett.

Finally, an image in which the subject is looking not at their work, but at the viewer. For a series of ads for then-Wulfsberg Electronics, this flight nurse gave us the perfect expression of seriousness and competence and pride. And it all started, and ended, with her eyes.