Specs:

Lens:
300mm

Aperture:
f/5.5 to f/22
6 bladed aperure

Closest Focus:
3.7m (12ft)

Weight:
860g

Mount:
M42

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

Image quality

Wide open:
Great sharpness
Mild corner softness but this never quite disappear on a fullframe.
Farly little vignetting

Renders very good at all apertures.

Build quality

Very good and solid.
Also have a nice feel exept for the aperture ring that lack resistens and don't have a good feel.
But that might be just mine.


Conclusion

Suprizingly good image quality.
Can be a bit tricky to focus a f/5.5 lens on a SLR intended for manual focus.
The focus aid doesn't work at that aperture.
Not a problem you find on a Digital SLR especially if you use liveview.


Thumbs up:
Image and build quality
Bokeh


Thumbs down




Technical Info
Scanner: Plustek OpticFilm 7600i
Film: Rollei RPX 100
Developer: Kodak D76