Of course, you can always remove the glass from the lens barrel, and use it for an auto extension tube. I have an extra 2x with a C/Y mount I've done that with, 25mm extension, and depending on lens coupled with it, I can get 4:1 or other variations. I wish I had one for my OM's, I also did it with a M-42 2x tele I had laying around. BTW, keep track of how it comes apart, and you can reinstall the glass, and have dual purpose.

Rick