John Lucas
Keith is dead on. Whenever you use a back ground that is brighter or darker than a medium gray the camera will not expose the image correctly. Cameras really only know medium gray and try to make everything that tone. As Keith said the camera tried to make the black into a medium gray and did a fairly good job of it. That of course over exposes the pen.
If you use a white background it's the opposite. The over/under exposure compensation button will usually do the trick. As he mentioned it usually has a marking like this +/-. Simply push that button and them move a dial or lever or what ever makes it go +1 or +2 or -1 or -2 until the exposure looks correct to you. Don't worry about how far or what the numbers mean just keep moving the dial one way or the other until the exposure looks better to you.