This is my first attempt to do volumetric lighting. I've added some light fog to the street scene, and I want shafts of sunlight to be coming down. I built a box [four deep sides and a bottom with holes] and installed spotlights shining down in it. But I can't see light shafts. The box is just above the camera frame. Can't bring it down any further. Is there not enough fog? Or, is this not the way to go? Gels, perhaps? I've yet to use gels either. What might the proper gel look like?

Did you activate the light cones for the spots that you want to see the light shafts eminating from? If not, you will not see any shafts of light no matter how much fog is in the scene. Lights in Carrara do not react to fog the way lights in the real world do. Light cones in Carrara are not volumetric, they are post render effects. Activate the light cones in order to see the shafts. It's in the effects tray for each individual light. To get your desired effect, try it with and without the 3D shadow option turned on.

WHAMO!! Nothing like Instant Gratification. Of course, much fine tuning of the light cones will be necessary, but that's for tomorrow. Thanks JayPeG.

When utilizing Carrara's light cones fine tuning is ALWAYS necessary. ;-)

You can have success....for example:) Feel free to ask questions if you have any problems with the light cones they can be tricky. Make sure to have 3d shadows set or they'll always look icky...at least I think so anyway

The light coming in through the window on the left is exactly what I have in mind. I'm seeing several shafts of light. Are you using several lights? Or a gel? Or does this happen by itself with a light cone?

Its that 3d shadows you need to have an object inbetween the light and the place the light is going to be going through

Yeah, I see what you mean - zones of light and dark in the volumetric effect. 3D shadows = dark areas in the dust or smoke.

Those shafts of light can happen either by using a gel in the light or by the light cone's interaction with surrounding objects. Light cones can be fun to play with, and gels almost always make them more interesting. Nice street scene, by the way....