letitlight

Check www.lightextreme.com for intensive courses in cinematography

I think you talking about a Night (?) Backlight your guys with 650 wih blue color ... the best would be to bounce it since moonlight is never so hard. Measure incident reading from this 650 pointing the light meter at it from their position. That f-stop you can use for your lens f-stop. As long as your interior is dark that will give you silhouette. If you want parts of your interior to be seen make sure its ambient reading falls somewhere at around 3 stops below of what the incident of 650 was. letitlight

for dealing with single light you might want to look up this guy at http://lightextreme.com/wst_page8.html letitlight

see what this guy does with one light ,... he has key, Fill, Background and Edge on the face www.lightextreme.com link "Light"