Specs:

Lens:
55mm

Aperture:
f/1.8 to f/16
6 bladed aperure

Closest Focus:
0.45m (1.5ft)

Weight:
185g

Mount:
M42

Covers:
Standard 35mm film size (24×36 mm negative)

Image quality

Wide open:
Great sharpness
Quite mild corner softness
Litte vignetting

Great image quality at all apertures.

Build quality

Very good and solid.
The lens have also a very nice feel to it.


Conclusion

Very nice lens with great image quality.
It's very well built and have a nice feel to it.

This is made for Mamiya's own m42 system which can use wide open light metering.
The apterutre ring have a little extra edge and a pin that this system use.
But this little edge will hit most m42 adapters and prevents the lens to be mounted all the way in.

Not seen any m42 SLR that have any problem with this extra edge.
And can be usually used without any problem but with stop down light metering.



Thumbs up:
Image and build quality
Bokeh
Feel


Thumbs down:
Can't be used with most m42 mount adapters.




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