Scrabble board lit with a single light from three angles
This is a technique which I've used on a number of occasions when I need to light something from multiple angles with a single strobe. I've covered it in an article for digital photography school sometime ago. The post is still available online at http://digital-photography-school.com/making-the-most-of-one-flash-case-study . More info after the jump.
The first step of the process is to capture the "base" image. As seen below, the base image is evenly lit (in this case by bouncing the flash off the ceiling). Whatever appears in shadow in this image, will be in shadow in the final image as well.
Base exposure used to produce the final image above
The "key light" images have to be captured next. In these images, a strobe is used to emphasise certain areas of the image. Typically a snoot or gobo will be used to control the direction of the light. The first key light image was captured to emphasise the tiles. A snoot was used to control the spill light here.
Key light image used to emphasise the tiles
The second key light image was captured to light up the area under the bag. Again, a snooted strobe was used to control the spill.
Key light used to emphasise the area below the bag
Once the image have been captured, I used a star trail action to merge the images. The end result is the image at the top of the post.
A tripod has to be used to make sure the camera doesn't move between shots. This ensures you avoid problems with merging the images during post processing.
This technique can only be used to photograph stationary objects.