I would take a look at the Bushnell Black Flash. The trigger speed it right around a .6 of a second so it should pick up anyone walking. It is a dark brown so it won't be detected or you can easily put camo tape around it. You can pick them up new on ebay for $190 from good sellers. The Covert is a good camera as well but run a lot of bushnells so I am bushnell fan.