With the kind of lens to subject distances that they are using with the 20X24 polaroids it takes stopping the lens down probably as far as possible in order to gain some depth of field. I'll bet that they are up in the 2000 watt second range or higher to expose the material. And at that the heads are probably in almost on top of the subject. Probably very confined area for the subject to occupy. The light to subject distance will prove beneficial since the light source will become effectively larger as the light to subject distance decreases. Less specularity will be the result.