The first thing to come to terms with is that you won’t have enough time, the location won’t be easy, and your subject will either turn into a wallflower or a Prima Dona the moment you train a lens on them. But, if your interview is well scripted and your lighting complements your subject and his metier, you’ll witness an almost magical transformation that can be quite revelatory.

Equipment

You’ll need at least two lights, preferably three. A soft source is best for your subject, a second light for the background, and a third for either fill light, hair light, or a side light (variously called "edge"; light or "rim" light). While you can get away with bouncing your light from an umbrella for your main or key, umbrellas tend to scatter light all over the place, making subtlety difficult. A softbox will control spill, accept gels, and offer other accessory options. I have a love-hate relationship with grids: love to use them, hate to pay for them, but once you do, you’ll know where the money went. They generally come in 20-, 40- and 60-degree angles. The smaller the number is, the narrower the beam will be. A grid will give you a soft, directional source-almost a contradiction when you consider the characteristics of most bare light sources. I’d go for a 16x22" box (which fits almost anywhere) or a 24x32" with a 300-500 watt lamp. Starting position should be 45° off axis both horizontally and vertically to the camera (see diagram). Used this way, you shouldn’t need a fill, but if you wish you can use another soft source on axis with the camera and 1 to 2 stops weaker than your main light. I like 12 x 16" softboxes for this, and again, a grid is handy. If you elevate the light slightly, a 20° grid should drop the light beam behind the subject after providing fill, without hitting your background.

The background light should be a controllable, directional source with some focusing capability, and it should accept barndoors, gels, etc. Choose an area of the location that represents the interests of the subject. Offices usually have bookcases, for instance; an orchestra conductor’s office may have a music stand with a score open on it, or a wall of the conductor’s favorite antique batons. A gel will add some mood to the scene and make the mundane a bit more exotic. 250-300 watts should be enough for this. You want to bring the objects into view, but you don’t want them to overwhelm the shot. Some specialty lights like the Dedolight feature optical projection attachments so you can add Venetian blind-like or leafy break-up patterns to the background. Rosco makes hundreds of patterns to choose from. You can even project a custom slide. Gridding your main light is especially important here to maintain the integrity of your carefully lit background.

An alternate set up (see diagram) uses the 12x16"; softbox as a side light instead of a fill. Place the light at the subject’s head-and-shoulder level and slightly behind, just glancing off the head, cheek and shoulder area. Again, a grid is handy in controlling spill into the lens. If you’re using a raw light, use barndoors for this. You might want to gel this light too: orange sidelight and blue background light or vice versa; the warm-cool color friction usually makes for a compelling image.