wow, I just saw this post with the images taken with the Helios modified glass. The bokeh looks so crazy. I have this lens and even used it on my mkii with an m42 adapter. but much more I love to use these m42 lenses (i have Asahi 50 and 28 as well) for the freelensing photography.
and the thing is, it is not that hard to modify. you just turn the front element. here is a really bad tutorial of how to do it :)
thank you, i will take a look. any way I need some special gear to open the screws :-)
it's very interesting - yesterday I found some great explanations on youtube, but it was very complicated by my opinion