You could also use Shader Mixer to create a desaturating shader, we had a discussion of this for a surface shader recently http://www.daz3d.com/forums/discussion/39846/ and a camera should also be possible. However, doing a colour render and desaturating it is probably simpler.
Comments
DAZ 3D does not do Black and White renders at default. You will need to convert a Render to Black and White in a 2D art program.
You could also use Shader Mixer to create a desaturating shader, we had a discussion of this for a surface shader recently http://www.daz3d.com/forums/discussion/39846/ and a camera should also be possible. However, doing a colour render and desaturating it is probably simpler.