Need some thoughts on this Christmas shoot.
 

Tomorrow I am shooting a :30 spot that will involve 2 kids and Santa around the Christmas tree on Christmas Eve.

We are shooting this in the afternoon in a totally light controled environment.

Just looking for any ideas about how to make this look like it's a dark house but still able to see the folks. I've lit for night stuff like this before, but never a Christmas situation like this so I'm just seeing if anyone has any thoughts.

Like, the tree will have lights on it. Anything there to be concerned with?

Any other thoughts on making this look like a nice, traditional Christmas scene would be appreciated!

My vote is to fake some candles or firelight. Put some candles in the scene and use CTO filters to bring a studio light down to the color temperature of fire (1800K?) and place it so it looks motivated by the candle (off-screen on the other side of the candle as the actors). If you can get it to look like it is flickering slightly, that could add to the effect. Be careful with candles as they are real fire.

If you have some windows in the set background, you can put a candle or even fake Christmas light design in the window. This will give you not only the light, but it's reflection in the glass. Put black velvet outside the window to make it look light night. There are lots of common Christmas light decorations for windows. Also, have a daylight-balanced light shining in from above the window to simulate moonlight.

If you want it to look more like night, don't light everything. Make sure there are a few areas in shadow. If the light is too even, it will look like a bright lamp is on or the sun is out. Make only one side of the actor's faces brightly lit. Keep the off side filled gently. For your key, I think you want a fairly soft light, so use a diffuser. People's eyes interpret dim light as diffuse light. I know, candles are a point of light, but people think they are "soft" light.

Obviously, the tree is going to be the most significant light fixture and you will need to decide if it is going to have white light or colored light. Bring sets of different colored lights. If you are using standard incandescent string lights, you might want to bring a dimmer for them. It will be a pain to re-dress a Christmas tree, so a big-budget shoot would probably have multiple trees so changes to the set could be made quickly. You will need to bring up or down the studio lights to keep your tree lights looking good. You don't want them to become overexposed so much that they highlight and lose color, but you don't want them to underexpose so they become insignificant in the scene. Personally, I would expose just enough so that they look bright but don't totally bloom and lose definition. I would want the studio and other practical lights to be just dim enough so there is a bit of the tree light spilling onto the actors.

Star or Spectral effect filters can be used to make your tiny points of light have star tails and colored blooms. Some sort of diffusion filter would give things a dreamy quaility.

I'm sure others will have more, even better ideas, but this is probably a good start.