I am directing a short that takes place in the back of a covered truck and am limited on cash. I was thinking we could make the truck cover out of a material that was thin enough so that the sunlight would hit it and disburse the light evenly throughout the truck bed and we could use natural light entirely. Almost like a giant diffuser draped over the back of a truck.
Does anybody know what material would be best and where to get it?
That sound like a particularly bad idea for several reason; the first is that in the real world I've never actually encountered such a vehicle, so the audience consciously or sub consciously might wonder what's going on. Of course if your project has a setting in the future or is a science fiction story where this peculiar truck bed setting would enhance the effect I'd retract my criticism.
If you never see the roof, it might work to construct the sides with darker canvas cloth, such as you might find used in such a truck and make the roof out of silk to allow in the soft diffused light you correctly seek. It would not be inexpensive to manufacture such a set. This is typical in many box trucks that have a white frosted plastic roof to illuminate the interior during the day.
From a lighting point of view, staging the action essentially in a white tent would be problematical, unless of course you want the actors to appear in silhouette. Is the covering complete including the back entry way or is that open to the daylight to allow a light source to enter? Is all the action in the daytime and/or at night? Obviously this would affect the type and quality of the light?
Also from a logistic point-of-view is the truck actually driving down the road as you shoot or being shaken to simulate travel. The lighting on the outside of the truck can indicate movement and or locale.
You might watch a movie that was just released where the whole film takes place in a closed trunk of a car. It was shot by James Mather the founder of the Digital Cinema Society.
Needless to say to do this convincingly will require considerable thought, planning and skilled execution.
Well, I'm assuming you have an establishing shot from the outside that shows how this truck has a translucent cover. Probably any white cover will work. After that, for the shots inside the truck bed possibly a frame with full grid cloth will work, provided we don't see the frame --which would be most difficult. A possibly less expensive solution than grid cloth would be to drape the frame in white parachute materials.