Well here is the result! I'm so excited I finally had the chance to try it myself. Few days ago i bought a M42 adaptor and now I use the Helios 44M-4 lens of my Zenit camera to my Canon Dslr. I already tried a few click and I'm super satisfied with the result, I think this lens is Just perfect for portrait shots. Anyway now was the time to try the bokeh effect because you have to set your camera to its lowest aperture value (completely open), and on canon's 18-55mm that wasn't possible(the lowest is f3.5), but with this lens the lowest option is f2! You can find online other shapes too if you want to experiment more and you can just read more tips Here or Here.
Good Luck!