my first 35mm had the same kind of focusing as the mamiya 7. It is hard to focus on dark things. What I did for that was take a flashlight (small one) and light up what ever I was focusing on at the time. then I switched off the flashlight. As for changing film, once you get a system going, it can be done quicker than you think. I am down to about 30 seconds on a change. Once you get comfortable with it and you know what the general settings are in your head for the lighting conditions, (you check using a light meter) you can shoot more rapidly. Mine the only thing that doesn't work with a dead battery is the internal light meter. I never use it, and forget to change the battery quite often. What I forget the most is to unclick the darkslide once I change film. that first shot after I can tell I did because it won't shoot. then you hear me cussing in Danish while tripping the button. I have the 43, 80 and 150mm lenses. Waiting for the close up attachment set to show up as I type.