How to Avoid Unwanted Side Lighting
Sometimes you need to shoot on location and do not have total control over the layout of the land. You may have to compromise where you place your lights, and this could lead to unwanted side lighting. How do you avoid it?
Pan the Light and Use the Barn Doors
You don't have any choice and need to place the light in a tight area so it will be out of frame. But, some of the light is spilling and creating unwanted side lighting. Before you add another piece of equipment into an already crowded area, see if there are options to manage the problem at the light. Maybe you can slightly pan it to get rid of the spill. If you can, then problem solved. But, you may have just caused another problem and need to pan it back. If so, try to close the barn doors to control the spill.
Add a Flag
In photography, we use flags to control and shape of light. Flags are made out of thick, black cloth that is sewed onto a metal frame. For a problem like this, you would probably want a 4x4 floppy. A 4x4 floppy is four feet by four feet. It has another layer of cloth sewed to the bottom of the flag. The top is connected with velcro. A 4x4 floppy can easily be turned into a 4x8 flag.
Flags have a small pin that is used for mounting. It can be grabbed by the griphead of a c-stand. When using a c-stand to hold anything, make sure the knuckle is on your right. This way, the weight of the object causes the head to tighten. If your knuckle is on the left, then the weight will cause the head to become loose and your rig will fall apart. Always place a stand bag on the bottom of the stand so it will not fall if someone accidentally knocks into it.
Open or close the flag to kill the unwanted spill that is causing your side light. The closer the flag is to the light, then the softer shadow you'll get in the cut.
There may not be any room next to the light for a flag. In that case, you can attach black wrap to the side of the light that is causing your problems. Blackwrap is black aluminum foil that you can clamp onto the light's barn doors with clothes pins.
Depending on your circumstances, one of these solutions with solve your problem.