Nice contrasty shot for the first photo! I am impressed with quality of the 40 years old lens! I think that not only the lightmeter is a bit off, I think your rangefinder also need some tweaking and also to clean up the viewfinder too. As for the shot of the dog, I think you are too close to the dog and beyond the close focus distance of the camera. Nick is right about PS tweaking for under-exposed shot. You need to adjust contrast and brightness till it looks well-exposed (but the grain will be more obvious). Most commercial shops does not scan them in color then desaturate to B&W but you could ask them.