I put a black background behind my subject (usually a flat black foam core board or a black cloth), and then get the subject as far away from it as possible, and only light the subject. Or I sometimes just shoot so that the background is in shadow if I'm on the road...
I do the same... try to keep your subject several feet away from the black background (I use black cloth). If my subject is near the background, I try to block the light from hitting the background with some kind of deflector.
If ou are unable to get a true black, a levels adjustment in editing will help, so long as it does not make the subject too dark. For printing, you can select just the background for the levels adjustment. For the contest, you have to make global changes unless the editing rules are waived.
g'day turbo. I too used a black cloth (an apron) on my kitchen table to get these. These backgrounds can be achieved without any touching up.
When I did these, the light first showed around the base of them. I redid them, with the object hanging over the edge of the table, in the dark, using a cigarette lighter for light-- To avoid seeing the cloth around the edges, you could say I did some dodging during the 15 second photo, by casting a shadow with my hand, on any areas in which I thought the cloth might show up. If you have a maglite, it would be much easier to 'paint' the light exactly where you want it.
I mostly do it with careful composition and careful exposure.
It is particularly easy with a telephoto / long lens as that allows simpler background selection.
Having a wide open aperture makes it easier because the background goes blurry.
Careful subject selection or lighting allows you to have a well lit subject and a background in open shade. It will not look like a black background, but will appear that way in the final exposure because of the dynamic range of film/ digital sensors.
Yes, this is different to the idea of dropping something in to the background.
The secret is in understanding exposure, rather than carrying a piece of black cloth around with you everywhere, or using flash. I find once you understand more about the dynamic range and what it actually means for your pictures, that these sorts of backgrounds become easier to do more intentionally, without needing props so often.
If you use a piece of black velvet for your background, it will completely *eat* the light. Just expose for your subject and voila! you will have a perfectly black background. (Be careful to keep lint and such off of the material - it shows up in photographs easily.)
