Grey, black & white, what have you, does not have to be solely accomplished through lighting. In fact it is less dependent on lighting and more dependant on the scenery and costumes. Take a look at our
current show
My Fair Lady. Those of you who know the show know that traditionally the scene at the Ascott races is a "black & white" scene; the women wear big fancy black and white dresses and hats while the mend wear either black and white suits or grey suits. So, look at this photo (for reference, our costumes are black, white, and grey with pink
trim):
Who wants to guess as to what colors we have in the lights that are on in this scene? Well, the primary light in this scene is from low sides in R44 (Middle Rose). Frontlight is pretty standard
McCandless: amber and blue, however we also have a rose frontlight
system in there too. I don't remember what the top /back lights are in for this, but I can almost guarantee you that there are very few, if any,
no color lights in the scene.
So, what's my
point? Well as you know there is no way to light in black & white. The OP says they need a "Film Noir" look. When you think about how these films were created you will realize that the
lighting designer had very little to do with it. B&W film did all the work and unfortunately, we can't just tell our eyes that we want to see B&W for two hours.
You actually can use many different colors of light and still achieve a B&W look on
stage. The key is in the costumes and set. Consider that for the most part, the more light you through on
stage the whiter it will look because when we (additively) mix all colors of light, we get white. Also, there is a very wide range of colors that can be used to set the "white
point" for a show or scene. There are lots of pale to middle lavenders, yellows, blues, ambers, and even a few greens that when used alone will be perceived at white. This allows you
shift from say a pale amber to a pale blue and while the eye will still see white it will appear much colder/bluer. Kind of like comparing the white light from an
incandescent source to the white from an arc source, it is still white, just very different white.
So sure, you probably don't want to light your
cyc with big bold colors if you are looking for a B&W feel, though lighting it with only
no color may feel odd. You might try an
RGB mix to white as it won't be perfect, but it will get very close and look more interesting. As for the rest of the
stage, you can use color and still maintain the B&W feel (as long as scenery and costumes plays along). You will be able to accent and set mood and tone and time of day with lighting, you shouldn't feel boxed into only using pale colors or
no color in your units.