With production lighting, certain productions may require you to light a car interior. Whether the scene takes place at night or during the day, this will require some technique.
Step 1: During the Day
Chances are that if you are lighting during the day, you should be able to expose the interior of your car. Not well, but there will be enough light. This may not be true if you have tinted windows, but generally, you should be fine. However, you run into problems when you start looking out the windows because everything outside the car will be blown out when you expose the interiors correctly. You may be able to coat the visible window with ND gel. This will bring down the exposure of the exterior, but will also cut down any light entering through that window. Thus, beginning the tricky game of balance. In this case, it may be important to bring out additional lights to night the interior of your car so the levels are closer to the outside. You should also note that ND gel is very difficult to make completely smooth so it may end up being more trouble than it is worth. If light is too harshly lighting one side of yours subjects face, try using a light panel like the Amaran HR672 to fill in the other side.
Step 2: Reduce Contrast
Since lowering the exposure of the exterior may prove to be unfeasible, you can now consider increasing the exposure inside the car. If you are going to attempt this with lights, you will need some strong daylight balanced lights. Try shooting some large 1k lights such as Light Storm 1s lights through the windows you are not seeing. With some diffusion, the light quality can be quite nice. You can also try to use daylight balanced Amaran HR672 Lights inside the car. Though this can get a bit crowded and difficult to control, you can easily run this small unit off of an inverter plugged into the car’s cigarette lighter or off of batteries. Finally, you can attempt to balance and harness the sunlight with a reflector. This causes a very intense, very hard light source which should only be used as a back light so you do not blind your actors. This said, it can be very effective though.
Step 3: Night-Time Lighting
Night time will not have the same contrast issues as day time. However, you will need to expose the scene otherwise you will be faced with a completely black picture. You can attempt to light it from the outside much as you did with the day set up. The trick is getting the light to look natural. If you can motivate street lamps, this should not be a problem. If you are only using moonlight as a source, you will need to use some finesse. You can also use the Amaran Light Panel technique inside the car. A very gentle glow from the dashboard is completely feasible. If you go too intense with the interior lights, the car will begin to look like a space ship.
Step 4: Managing Movement
If your car needs to be moving during the shot, you will need to have all your light sources moving with it or the lighting will appear to suddenly change when the camera moves. This will not be a problem for any lights inside the car powered off of an inverter or batteries. However, for any lights outside the car, you will need a trailer to attach them to. This is usually very expensive so you may need to avoid such sources all together. For night scenes, you may be able to keep the car stationary and create an illusion of movement with some moving lights. You will have to compromise by only seeing black out the window, but the effect will sell.
Step 5: Don’t Over-Do It
Remember that as with any lighting, it is very easy to do too much. If you use too much lighting, your car will begin to look like the interior of a space ship. If you use too little, it will appear dark. Remember to balance your lights and keep the scene subtle. If it is night-time, maybe it is best to keep it a little dark. If it’s day-time, you should only need one or two small lights to balance it out.