If I can add my 2p here. I'm not sure what other cameras do, but Nikons have a P mode in addition to auto. In 'P' the camera is still choosing the exposure, but it allows you to scroll through the various options e.g. 1/125 at f/11 is the same as 1/1000 at f/4 (assuming I've done my sums correctly) I assume this would still be allowed as you're going with the camera's settings, but it allows you to control DoF.

One quick question of my own now, my black object is quite shiny and has a couple of bright spots on it due to reflections from the window. Is this acceptable, or does it need to be totally black?

Cheers

Paul