Thanks, yes I really like the system, it makes it so much easier to decide what combination to use. I'm pretty good at judging the number for ISO400 now in my head. Where I struggle is going the other way around - the Aires has a 'snapshot' setting at f6.6, focus to 10m and you get anything from 4m in focus, but then I need to think about the shutter speed... however I have two light meter apps, one for EV and the other with f6.7 locked to give a shutter speed! That's when I'm not using y Westron V.
In other news; I just followed the instructions in the video on page 1 and cleaned the rangefinder and viewfinder of my original - and it's now as good as the new one! Really easy to do, luckily nothing needed re-glueing