If you have the mamiya 43mm, and the decision is between the 50mm or the 80mm, it is clear that you'll get much more focal length versatility with a 43/80 combo than with a 43/50 combo. However, if you are trying to decide between a "standard" focal length 80 or 65 to combine with your 43mm, then that's a harder decision which you'll have to make in terms of your thinking about the 3,5cm focal length ... the 65mm is just slightly wider than a 35 (~32mm in 135 format), whereas the 80mm is slightly narrower (at ~ 39mm in 135 format); which is to say, not a massive FL difference. I went with the 80/4 as my standard mamiya7 lens over the 65mm because I prefer its slightly tighter framing as well as the slightly smaller form/weight of the 80mm... But there's nothing for it, the rendering of either lens is just great.