Stephen,
That sort of solution can work well for you.
Or perhaps you use nothing: be aware of the light falloff properties from your newly acquired lighting equipment, and use that to your advantage.
If the room is deep enough, you can just allow the light to not illuminate your background areas, and thus it will be naturally dark. You'd probably want a little more than twice the distance from your light source to
model as the distance from your
model to your background. Then, by using a suitable aperture setting on the camera, there will be very little light hitting your background that your camera's sensor will capture.
In terms of size, I'd be looking at something that's significantly larger - 12' wide minimum, really. As your background is behind the
model, and you change your angle of view to your
model, different areas of the background may come into and out of your camera's view. anything much narrower than 12' may cause you issues in that the edges - and uncontrolled backgrounds beyond those edges - may come into view.
In terms of colours, I'd probably consider getting a couple of different sets of fabric to use here. White and black (one of each) is always a good starting point. Then consider a couple of pastel colours. If your lighting gear has provision for gels, use one light, with a coloured gel, on a white background.
Also consider using a very light white fabric (muslin?) over a window area as a light source. This can give you a good, large light source that you can use for the images that you're considering.
Finally, and most importantly, congratulation on the pregnancy and upcoming happy event. I wish all three of you well and much joy and happiness.
g.
Gary Stark
Nikon, Canon, Bronica .... stuff
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