Jay P Morgan of The Slanted Lens posted a pretty great lighting tutorial in which he focuses on "snoot" - an object that you put over your light to control the direction and radius of the light beam. This technique is usually used in photography and in film noir, so if you plan to shoot the next "Sin City", don't miss this video! Jay P explains that in film it is a good idea to use black wrap to create snoots, for example black aluminum foil that can be formed into a funnel and molded to the light. This technique is so popular in the case of film noir because it gives your footage (or pictures) a lot of contrast and this is often something you want to get while shooting black & white video. It is also a very directional light, so you need to take this into consideration while lighting your scene. Check out the tutorial for more info:
And what is the area of coverage of a snoot? Jay P explains:
"This is a hard question to answer since there are many different sizes from different manufacturers and you can make your own. The one I have is fairly average so let’s look at how it compares to a grid. I shot an image of our subject against a white wall with the light eight feet away and a second on set. The area of coverage is very narrow and the fall out is very sharp. There is a certain amount of fill in the dark areas when we shot on the white wall but I don’t think the snoot was sealed well enough to the instrument. Images using a snoot usually have a very concentrated area of light with no fill in the shadows. Compare this to a shot with the same setup using a 10 degree grid. The edges are softer with the grid, the light falls off much faster and there is a hot spot in the middle."