We needed to take a photo in our daylight studio that showed a person working late at night on a computer. Problem was there was full daylight coming in from the windows behind the model and elsewhere in the studio. So the problem was to block out the light to a point where the use of ambient lighting from a desk lamp and the computer would balance with it.
The LED lights I spoke about in a previous post were used to provide a cool illumination from the laptop. The desk lamp gave off a warm glow. By shifting the color balance to diminish the warm tone, a cooler blue tone resulted in the rest of the image to enhance the feeling the photo was taken at night.
We blacked out the window with large foam core flats. Later, in post processing, I allowed a night shot of a city to bleed through the black windows. The photo below shows the actual scene used to capture the image. The lamp in the back left served as a hair light. In addition to what you see here, we brought in another black flat to reduce the light coming in from the door on the right.