Most of the cameras I build have the zeise rangefinder except for the new view type cameras I have begun to build. I just could not get the last one to focus to save my butt. Outside it was too bright without the cloth and that was too hot to spend much time critical focusing. In the studio it just would not focus. I just knew my shooting days were over. Then I raised the wattage of my lights.... Doubled it actually, and wa la The camera suddenly got sharp. Ain't the gettin' old challenge fun?