I just started on the "old glass" and have been learning all about manual focus with my M 50mm 1.7 and 1.4.
I've been super impressed with low light shots - I can do things with these two lenses that I could never do (or struggle to do) with my sigma and DA kit lenses.
All shots were shot wide open on Av setting.
Some shots with the 1.7:
I don't know if you can tell with the orchid picture, but when you zoom in you can actually see water droplets above the flower itself. And the droplets are perfectly clear without any aberrations. AMAZING! Almost makes me think I don't need a macro, and just more patience. ...almost..
This was taken with the 1.4
As you can see, I'm spending a lot more time with the 1.7 as opposed to the 1.4. Getting the focus *just right* on the 1.4 is a bit of a learning curve. But I'll get there... eventually. I must say though that these two lenses have spoiled me when it comes to sharpness. Most of my other lenses aren't really stacking up in comparison.