Specs:

Lens:
300mm

Aperture:
f/4.5 to f/22
19 bladed aperure (Preset)

Closest Focus:
3.3m (11ft)

Weight:
1863g

Mount:
M42

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

Image quality

Wide open:
Not crazy sharp
Fairly mild soft corners
Little vignetting

Renders very good at all apertures.

Build quality

Very good and built like a tank.


Conclusion

Real monster of a lens!
Image quality wide open at infinite are not crazy sharp, closer subjects looks great and feels nice and sharp even wide open.
Renders very well at all apertures and the bokeh looks great.

This is a quite old lens and I would guess somthing like the 50s-60s with the exakta mount.
Build quality is as a rock like most camera gear from this time.
But its huge and heavy.


Thumbs up:
Built like a tank
Image quality
Bokeh
19 bladed aperture
Closest Focus: 3.3m (11ft)


Thumbs down:
Huge and heavy




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