I'm continuing to play around with the reversing ring. I knew that I needed to stop down the lens to help get more things in focus. However, I wasn't sure how to do that with a reversed lens. I discovered that the only way is to mount it normally, set the desired aperture, press the depth of field preview button, and then unmount the lens. I'm hoping this doesn't ruin it, but it's just my cheap 50mm anyway. The other downside is that my sensor is probably getting even filthier than it already is.