I tried for several years to get an image that was, an impression and just black. I started with the Threshold tool and failed but then each time I tried I got a little nearer, gave up and started again a few months later.
Eventually using Ps7 and Ps13 in tandem I arrived at this one, my first success.
It's an old quarry almost completely overgrown, it rained when I got there only showers though, this image was made when the sun shone briefly through the trees.
You will see grey in this image because it is a considerable reductions, the originals are just Black and will print beautifully from a cheapo Laser printer. (that was a bonus I bought one for £30)