The 4 images below I decided to try out the lens on an overcast day. While you don't get the contrast in the sky so much - the contrast on the features below turned out just how I hoped they would. I've posted 2 versions of each photo - the original and the converted black and white. The red photo is the original and is how the images looks through your view finder.
The Red 29 filter is a very cheap and fun thing to have in your camera bag. I definitely recommend one for any photographer who is interested in shooting black and white images.