[ updated ]
lightf/x creates lightarrays or lightstrips; groups of lights arranged in a pattern.
Because of the multiple lights, the resulting shadows are much smoother than from a single
light. Of course, your render times will be greatly increased, but the final result is
worth it. You need to have a local light selected for lightarrays, or a spotlight selected
for lightstrips. lightf/x uses the first light for positioning and to base its color,
intensity, and shadowing values on.
tip: If you don't need reflections in your scene,
remember to reduce all the trueSpace raytrace settings to their minimum. This will let you
keep the soft shadows but lower render time.
faq: This takes ages to render, what use is this?!
Take a look at what you get. You can't get results like that
without a lot of lights. C'est la vie =*)