If i'm not mistaken this is one of the older M42 mount lenses and I would guess around mid 50s to early 60s.
But have unfortunately not found all that much info.

Specs:


Image quality


Build quality

Very good and solid.
Also have a nice feel to it.


Conclusion

Nice vintage lens with a lot of character.
Image quality wide open is not very impressive technically.
Okay center sharpness but bad corner softness and quite a lot of glow.
But I like the dreamy image feel this gives.
And stop this down and you still get quite sharp and nice images.

The bokeh do mostly look quite good but is sometimes not all that smooth.
Flare is huge and I must say that I love it!
Almost like a cartoon flare with tons of sun rays.

Really like the lens exterior look but it is quite the small one and can look a bit out of place when mounted on a bigger camera.


Thumbs up:
Image quality (vintage feel)
Bokeh / Flare
Build quality / Feel


Thumbs down:
Image quality wide open (if you don't like the image feel)
Corner softness
Closest Focus: 0.8m (2.6ft)


Technical Info

Analogue B&W film
Scanner: Plustek OpticFilm 7600i
Film: AGFA CINEREX (X-ray film)
Developer: Kodak D76

Digital
Canon 500D with lens mount adapter
Auto White Balance and ISO 100