What about doing everything in post? i mean masking or vignetting?
Masking is tedious, vignetting probably will leave a 'halo'. Sure, you may be able to cut out some large area with a garbage matte, if 'grey' if the area around the subject can be 'crushed' to black.
You need about 3-4 stops between the talent and the 'background', and an uncluttered back ground would be 'good', to allow you to adjust the low end of the curve to drop out any residual 'dark objects'.
If 'money' is a problem for expensive photo backdrops, black sheets from Target/Walmart or similar department stores will work if doubled up (if one is shooting in the ordinary apartment/house that has light/white walls.).
As mentioned, controlling the light so it is only on the subject, and there is no 'bounce' will also add to the 'in camera contrast'.
Edited by jeclark2006, 07 July 2014 - 01:06 PM.